The only concern I'm aware of would be whether or not the chip matches your transmission; manual vs automatic. The chips are not interchangeable across the ECMs however, so the 85 chip must remain with the 85 ECM and visa versa.
Thanks for the info. I swapped the 85 ECM into the car and the idle is much more stable, arount 1000 rpm. However it dies coming to a stop when the engine is cold. Do I need to recheck the initial timing with the new ECM?
The original ECM started keeping the idle high for an extended period of time. When it finally did idle down the car woud almost die and then the idle woudl kick back up to a higher than normal idle speed. My car is a 3.4 PR. I have heard that a custom chip is necessary but my engine ran well with the stock ECM for about a year. I have checked for vacuum leaks and not found any. EGR seems to be fine but looks to be an aftermarket unit.
You may have a problem with the TPS sensor. Some times the contact point in the closed throttle area wears out and causes an erratic signal destabilizing idle considering the motor ran fine before for a year.