Mitsubishi Repair: Idling problem, exhaust gas recirculation, eclipse gs

Question
My 91 eclipse gs turbo fwd is idling between 900 1200 rpm and won't stop even after it warms up.It will not shift into any gear after I start the car. Also is there any difference between an ECM for an automatic and an ECM for a five speed if it's the same year car, both turbos.

Answer
Jossie,
Your bouncing idle (sometimes called idle surge) can be caused by a malfunctioning ISC (idle speed controller) and/or a bad EGR value (exhaust gas recirculation).  It's not uncommon for an ISC to wear out on older cars with high mileage and that do a lot of idling.  You may need to replace it if this is causing your inability to shift.

There are differences between an automatic ECU and a 5-speed ECU.  I don't know the full extent of the differences, but I would not replace one with the other just to be safe.
Good luck!