Well I thought it was a boost leak as the symptoms feel the same. It bogs and hesitations. Feels like major turbo lag and then slight power kicks in and out and I can see the boost building but no power... I've used boost leak tester and no leaks... Even changed all the t bolts and couplers. Same problem.
 
I wonder if the issue is related to the cold start injector time switch. That's broken off completed from the coolant tree... What kind of symptoms would that cause if it's snapped off?

Could the problem be the knock sensor? I can't check for codes as I noticed the cluster is missing the engine light globe and connector.
What are the symptoms of blown knock sensor?

1st thing I would do, is replace the engine check light globe / connector & see what codes the car is throwing out.
A faulty Coolant temp sensor can also display the symptoms your explaining.  I doubt its the knock sensor, they too will throw on the engine check light if reved pass 2500-3000rpm.
 
Could even be either bad plugs or leads too.

You need to start with the basics and go from there, as above replace that light and check for error codes no point in speculating yet if the ecu is going to tell you what the problem is.

Yeh, get globe and pull codes. Def could be knock sensor. Gen2 or 3? Could also be afm, or a leak between afm and turbo.

Sounds like a fuel issue to me. Blocked filter or faulty fuel regulator.
Maybe fuel cut from boost spikes if the waste gate isn't opening properly? That would be quite sudden though-doesn't sound like that.
 
Usually electrical gives misfiring.
 
Faulty sensor signals can engage "limp mode". That's very possible. Eliminate those (fix em) first and check ya fuel pressure I reckon

Thanks guys... taking the cluster out was a pain in the ass but it's on my list to do... I've done a lot of research and I think it's the knock sensor... fuel issue did cross my mind... I've taken the plunge and ordered the ATS knock sensor... I think I'm stuck in limp mode... If it doesn't work then I'll take out the cluster over Christmas and source the engine light connector and globe.

On another note, I read that you can tell if the knock sensor is blown if you take it off and give it a shake... if it sounds like a blown light bulb then it's blown. I think I'll get under the car after work and see if I can take it off and have a listen
 

petmr2
Thanks guys... taking the cluster out was a pain in the ass but it's on my list to do... I've done a lot of research and I think it's the knock sensor... fuel issue did cross my mind... I've taken the plunge and ordered the ATS knock sensor... I think I'm stuck in limp mode... If it doesn't work then I'll take out the cluster over Christmas and source the engine light connector and globe.

Big mistake to use the ATS knock sensor if you are still running the factory Toyota ecu.  If ATS is still supplying the GM knock sensor as replacement it is not compatible with the Toyota ecu.  I have done some considerable testing on both sensors and the are very different in many ways.

Hey dude, what year model is your car? Do you have issues starting it sometimes?
I had a similar issue with my 91 Turbo, it turned out the main power wire to the rear fuse box had corroded at a factory splice point. I had a spare Gen 3 loom from a 94 Turbo, when I stripped that down to poach the main power wires it seemed to be sealed up much better than the 91 loom, so if yours is a Gen3 this might be of no assistance.
http://www.mr2australia.com/mr2play/tm.aspx?m=121791 
Easy enough to confirm, just remove the 15A EFI fuse and stick the multi meter probe in pin 2 which should be the one closest to the ignition main relay, even if it gives a good reading try jiggling the wiring around from where it splits off to the engine bay temp sensor.
Good luck!