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?

[lagos]

Yes, I checked the pins twice to make sure that they were pinned and seated correctly.
Car drives 110% better then it did on the stock ecu with no codes. Only issue is that it idles at 950rpm.

Timing was set to 10tdc prior to the ecu swap.
If I try to put the car into diagnostic mode now, it wants to stall out badly (sometimes it does). Then after a few seconds it will recover and bump the idle up to about 1200rpm. If I try to set the timing at that rpm, it will probably read incorrectly since the engine is revving that much higher. Even if this was a timing issue, I dont understand why the car would want to stall out so badly when being put into diagnostic mode. If the timing on this ecu was off, it would only be by a small amount, and shouldn't cause an issue like that.

93's did get a different igniter. Im thinking that my old one is probably reporting the wrong rpm to the ecu. I'll have to track one down to try it.