Some interesting info in this thread. http://www.mr2.com/forums/threads/60229-Intake-pipe
 
What is the inside diameter of your MAF section of piping?

I'm likely to clean it tomorrow at my mate's and buy a can of Throttle Body cleaner to do the job etc.
 
I can try measure it with a ruler or something then!
I'm also sussing this thread out as I write this :)
 
Thanks for all the info, hoping to get some good results out of the clean & later the SARD intake.
Really don't want this to be a more involved issue like spark plugs or fuel pump etc. :/

So I took the pod filter off, then the MAF, then the large elbow intake hose.
The throttle butterfly seemed fairly clean as is, I gave it a good all-round spray with the cleaner I bought and wiped it down anyway.
 
I put everything tightly back together; not much of a difference. Still 1-2 hesitations till I hit 4k RPM & the engine struggles to drop RPMs when I let off the gas and clutch. If I clutch when I had not pressed the gas recently it's fine, otherwise the responsiveness of when I let the gas pedal go is delayed.
Throttle body seems to open and close rapidly, so the issue isn't there.
 
It's also worth mentioning that when the weather gets cold (12C or less-ish) I struggle to start the car, always starts in one crank, but it used to take a few good seconds and when it starts you can hear the engine struggle for a few moments (almost sounds like it's coughing) before it raises its Idle RPM so it can warm up properly...
 
Also, worth mentioning this too, I sometimes hear a whoosh noise (like a blow-off valve almost) when I let off the gas at high RPMs.
An easy way to replicate this (and I did it today after cleaning the throttle body), was to take the car to 4-5K RPM in 2nd, and let off the gas, I hear a whoosh sound for like 1-2 seconds... No idea why or how or where that's coming from.
 
Anyway, I'll be getting a hold of the SARD soon, waiting to hear from Gorilla Industries to see if they can help me out for a decent price.

I'd be looking for air leaks... Get a cigar and start blowing in to tubes

BEAMS engines have only one vacuum tube, so it's not that likely to be an air leak.
 
As has been said before, it's probably that your ECU isn't getting the right signals from the MAF (due to the incorrect air intake and intake diameter), so the ECU isn't behaving normally. This will be even more pronounced during cold starts.
 
Unless the intake issue is sorted/eliminated first, trying to find other sources for your problems is like chasing unicorns.

That makes sense @mister2. I'll update everyone once I get a hold of a SARD intake :)

One other thing to be aware of: Once your ECU has been disconnected or otherwise reset (by disconnecting the battery for example), it will take 10 or so minutes for it to "relearn" the operating conditions and begin behaving properly. Until then, the idle speed and fuel/air ratio will wander about... so don't freak out if you don't get instant results. You won't – and that's perfectly normal.
 
   

My stock '90 model Gen2 NA does something similar.
When I first start up after the battery has been disconnected I notice that the idle speed is 300-400 rpm higher than normal, and I have to drive it for about 10 mins before it settles down to idle normally.
 
If you want to avoid that happening, you can get an attachment that is powered by a 9V battery to plug in to the cigarette lighter before you disconnect the battery.
http://www.ebay.com/bhp/memory-saver
 
 

@Reddtarga No I think the aim is to GET that to happen after I change the intake to something better for the engine!
That way the ECU noticed new readings and readjusts accordingly.

I can however see how that might be annoying for someone who might be constantly disconnecting the battery/power from their car without changing anything affecting performance.

So I asked someone who sources MR2 parts and got this response and diagram. But have no idea what I actually need from it... Can someone please help out?

"Hi Andrew, Sure we can assist with these parts, these are parts we would have to order in new for you, all of these parts are discontinued from toyota however i've contacted my supplier in Japan and they have confirmed they should be able to source most of them, I will be able to give a better indication on availability once I know exactly what you require here is a exploded diagram below this should hopefully look somewhat familiar to you 17881 is the elbow/ S shaped intake pipe you mentioned the air intake box was available in sections or as a complete assembly, the sectional availability is now completely sold out so it would need to be purchased as a complete assembly,
I am not sure if the MAF sensor is included in the complete airbox assembly given the part number is raised above the complete assembly i'd say it isn't (although the price would suggest it should be) however it might be I can order the complete assembly in and if the MAF sensor isn't there but required it can be ordered separately, it appears there is a resonator chamber which attaches to the main air intake and then 3 more resonator chambers and air intake duct pipes which I imagine are pre-air box if you let me know which parts off the diagram you require i'll confirm availability and pricing for you,
Kind Regards
Josh"

Thanks guys! :)