93 ecu on a 90 swap. Options

[lagos]

I installed a 93 mr2 ecu in my 90 3sgte. I repined the harness plugs to work with the new ecu. The car drives perfectly but wont idle correctly. It will sit at 650 rpm and want to stall out. Then after a few min of driving it will bump itself up to 950rpm for the rest of the drive. If I put the car in diagnostic mode, it will stall right out.

I was thinking maybe it has something to do with the IAC valve, but wannabe confirmed they should be the same. I know 93s have a slightly different throttle body, so maybe that has something to do with it.

Anyone here use a 93 ecu on their 90-92 motor?

[DEATH]

Mine was too before the engine came out to be rebuilt but I've been all over the vacuum lines and everything so I'm pretty sure it's not that. Like I said - mines just a slight flutter at warmup but it's annoying when everything else on the car works so well now. I know it's nothing with the engine itself - I suspect it was some minor difference with something between the gt4 engine and my friend's experience with only SW20's. IDK - It's like 99% there but that extra 1% makes the completist in me angry.
If you need anything, pics, me to try various BS with mine, w/e - LMK. I'll be more than happy to help you experiment in fixing your problem.