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Galant - RPM oscillates at Idle

I have a 1995 Mitsubishi Galant, 5-speed manual trans w/over 160k miles. The engine idle oscillates at idle speed, (700 to 1500 RPM) but it runs fine at all other driving conditions (anything off idle).

The condition starts a short time after the engine is first started, from maybe 15 seconds in warm weather, to maybe 60 seconds in cold weather.

I’ve cleaned the idle air bypass valve and the condition continues.

My question: as the replacement sensors and other related parts are very expensive, I’m hoping someone has had this experience and can point me to the most likely part to replace, or other assistance.

I would like this car to last another year or so and am not inclined to put a lot of money into it. This condition is more of an annoyance than a ?necessary? repair.

Thank you for your help.

Before you start throwing expensive parts at the problem, first check the engine for any vacuum leaks. That can cause the idle to fluctuate.


check the idle control module,lives on the ECM, and the ECM.what codes?theres always a code when they idle this way,(so dont tell me there are no codes present)I know better.poss no comunication?

check throttle body for filth,then do a minimum air flow test with the proper scan tool,how does theCTS reading look? did you play with the BYPASS SCREW ON THE THROTTLE BODY BY CHANCE?

pull the IAC connector,turn the key to run and check the voltages,for pulses on 1-4?

2-3 pins results? this will tell me what has gone south.

let me know.

good luck.