Finally!! It's idling and running stable and like new again. Here's an excellent procedure on how to isolate the idle speed stepper motor from the ECU, reset it and then set the idle. Much easier to follow and better illustrations than most shop manuals.... http://www.vfaq.com/mods/BISS-1G.html

It's amazing how "easy" it was now that it's all done. LOL!!! Edison was right about it being 90% perspiration.

Bob

"Guv Bob" wrote in message m...
My 1990 Mitsubishi Eclipse (DSM 1G 2L non-turbo) is starts and idles cold fine, and runs fine warmed up. When warm and I put it in neutral (AT) the idle oscillates between 1800 and 2200 with about 1/2 second cycle time.

MAS was the first guess -- so I put a rebuilt mass airflow sensor assy in and same problem. Checked all the connections and vacuum - all OK.

Also took the throttle assy apart and cleaned all - helped the running but still oscillating. Cleaned Idle air motor, checked voltages and resistance for all sensors and also voltages coming from the computer, and all OK.

About out of ideas -- anyone have some thoughts on how to start troubleshooting this?

Thanks in advance.

Bob