Sorry to hear of your overheating issues.
I had exactly the same symptoms on my previous 3S-GTE engine after Mr T flushed my coolant.
Did all the things you've listed with no effect, ended up swapping in a Gen 3.
I highly suspect that the initial problem was compounded dramatically by me continuing to driving it around after the initial overheating event, (with one eye on the temp gauge and a hand ready to turn the heater on), to the point where only an engine rebuild or swap would solve the issue.
 
A couple things you may want to check;
Warm engine up with radiator cap off, do you see bubbles coming out the filler cap? If so it's probably the head gasket or trapped air in your pipes.
There is also a chemical test you can complete, that checks for engine gasses dissolved in your coolant, this would again indicate the head gasket or crack in the block.
I had my coolant system pressure checked, all was fine pressure wise... but I'm sure now that there was probably a micro crack in the block or warped head/head gasket which drove engine/coolant temps up.
 
I hope this helps and wish you luck with your MR2.
 
 

i told you before and im telling you again, thats the worst plumbing job ive ever seen, im betting thats where your issues probably are.
i would do a proper plumbing job and use the bypass hose if yours still doesnt have it and see what happens
 

Hey DVSTurbo2 thanks for the advice I've stopped driving her since...yesterday
I did that chemical test you mentioned on Tuesday and it's all fine. When I drive the car hard after a warm up there's no probs at all. It's only during the first 20 mins of cold start but that's enough reason to not drive it.
It's all good now I've passed the stressful bit as I know what the problem is now. Just focusing on the positives like being grateful to have a car lol etc

Final update, closing this chapter once and for all (hopefully)!
Well I got her back from IDB today with Beams spec water plumbing and even Beams spec fuel lines. Very pleasing to the eye.




 
Due to the intake setup obstruction the coolant filler neck hose had to be modded. I think the airbox position is constraint by the wiring length which in turn was largely due to it being completed long before the mechanical fittings were finalised.
Big thanks to Mandalay for the outlet, fuel lines, Road & Track for the water hoses and IDB for putting everything together. And thanks to everyone who posted for support!

Hopefully you can start to get some enjoyment out of your car.

Theres no shortage of us putting lots of $ for minor miles.

Thanks mate. Engine wise I'll admit that it's been quite troublesome for such a little NA. If I was solely into cruising and show and shines I reckon it wouldn't have been as hard to get that same feeling of "enjoyment" but unfortunately motor racing had to be my poison and potent it has been! At the end of the day it is a 20+ yr old, mid-engined sportscar
I'll def be getting some in a few weeks!

Rage. Just subtle, silent rage.
Well it's been a few weeks now and after getting all this stuff done and the amount of cash poured into this vampiric money pit I've been having a few bouts of overheating. But it's just so inconsistent. Car has an attitude, big time.
First started with cranking the engine from cold, temp gauge went half way, then back down. So I decided to bleed/fill it but here's the strange thing: there's air bubbles coming from the filler cap but the level does not drop! Put the cap back on, went for a spin and goes to max. This time I bled it with cap turned to one click, let it idle for a few minutes for 2 sessions just to make sure all the air is pushed out. Although this is a step in the proper bleeding procedure, it shouldn't be necessary to be this extreme. Anyways it's good for a while so I decide to have my fun.
At the beginning of my "hard run" there was one episode of temp reaching max. I hoped it would pass and after a few seconds it did. The rest of the night I went hard for at least 1-2 hours and it was all good.
I still couldn't figure out why last time I bled the car with open cap air bubbles came out (began to suspect HG) so I tried bleeding again with open cap. No bubbles. System is full as it's always been since I got it back. Even gave it a few revs and no bubbles. Drove to my mates house and it reached max 3 times. The needle wouldn't go down unless I opened up the cap (carefully) each time to let some gas/air out (presumably). And this happened during light load dafaq...
I don't have caramel oil cap, the car doesn't smoke at all, the coolant system is always full when I check in the morning, the engine goes hard, I even got a decay test with positive result. But everything seems to be pointing at very early signs of head gasket issues. Somewhere air/gas is leaking into the water system, me thinks. I've already paid and registered for the Big MR2 Trackday and I'm reluctant to pull out since I might get into deeper excrement. The only thing that hasn't been changed in the water system is the temp sensor, but I highly doubt it the culprit. There's no shortcut to a HG job but I think this might be worth a shot in the short term:
http://liquidintelligence...own-head-gasket-repair
I'm still in the early stages so it's meant to last me several years or so but track days will probably cut it down to 2-3 months, at least until I become a millionaire. Yep I'm pretty ticked off but just not ready to sell her just yet. Gonna use this rage to fuel my drive for millionaire.
Has MR2 ownership actually made me dumber? If we treated our partners the same way we treat our cars there would be no conflict (on the contrary we would be at their mercy lol)
 

Just on a side note i think your missing the lateral engine mount on the gear box ? The starter also looks like its missing a bolt. I have no idea what the wire is on the manifold shield but move it, it will melt !
Since you want to track
 
Now to the over heating. 
First are your fans working properly ? They dont run as soon as you turn on the ignition, only come on when about 88 degrees ? If not first disconnect the temp sender on the radiator. The fans should come on , do they ? If they are on all the time very good chance the A/C amplifier is dead.
What coolant are you running , hope its the red ?
Bleed as per BGB with the 2 hoses connected to the frunk spots. Heater valve and radiator.
Did you put in a new thermostat ?
I know its harder to see the engine coolant overflow bottle due to the position but that level should change by about 1-2 cm when the engine is cold and when the engine is turned off and hot.
I can clearly see that since i moved my bottle to the boot.
If you are still having airbubbles in your system it is not working under pressure as it should  and obviously you have a hole somewhere. It needs to be pressure tested.
 
Also im not convinced you have the bypass done correctly , again it looks like non-OEM parts were done going by the hoses i see on the fire wall ? Is it done properly.
I know im an OEM freak but other parts can be used as long as its done the same way but generally speaking they arent and thats what causes problems.
I cant help stating get the system pressure tested, get a new thermostat and put all the OEM pipe or at least the correct way and im sure you will have no issues unless you have  HG leak and or the fans also are not working the way they should.
Man you should of got all the parts that were missing from day one while the engine was out :( 

Mate not a day goes by that I wish I had done everything correctly, taken it to a better place while it was under warranty. But it can't be helped now, it's all in the past (experience) now.
That wire is the O2 sensor, auto elec says it should be okay but I will re-locate it for insurance. Fans are working just fine when I turn it to the ON position. Thermostat changed twice, it's genuine now.
Trust me the system is fully bled properly. There is a line between perseverance and stubbornness, sometimes you have to give up. There's only so much you can do for bleeding, then you have to look at other areas, says mech.
Is it still not OEM? I thought I got the right parts from them :/
 
Mandalay I think you were right (unfortunately in my case) in your post on the MR2 Beams forum about my car slowly overheating due to too many incidents. I think a pressure test is in order. Even then this stupid car only acts up when she wants to, such as the decay (combustion gas) test. It really varies when the gauge goes to max.
I'll check the spark plugs tomorrow.

I like to work on my car that way i know everything is done and done correctly.
Your issues are mainly due i think to incorrect plumbing and the other things that have been left of either because you didnt supply the parts but even worse these people have not told you that it is missing. The bolt on the starter, the lateral link and God knows what else i havent picked up :(
 
These 2 lines on the bypass are not OEM. That is not a real problem but what is , IS are the plumbed correctly ?
Top one to the water outlet
Bottom on to the return of the bypass pipe
Do you have the 2 water lines to the throttle body ? If not how did you plumb it ?
 
This is OEM
 

 


 
Missing latteral mount

 
Missing bolt on starter :(
Also on another note the plug on the water temp sender looks wrong . Even tho the EPC shows 2 wire its actually a 3 wire. Earth , one for the ECU and another wire for the gauge. So i have no idea how yours is wired ?