Hey guys, long time no see... I'll get right to the point... 1991 Eagle 2000 GTX FWD 2.0L 4g63 SOHC 5 spd.

Every once in a while, the idle goes all funny at approximately operating temperature. Last year during a 15 hour trip to Raleigh, NC., the car went idle hunting whenever I got off the throttle. I replaced the air filter, adjusted the idle, adjusted the timing, but the problem kinda persisted until it went away. Now, ever since yesterday (incidentally, it was raining pretty heavily), the idle drops to about 500 whenever I let off the throttle (IE: coming to a light, or shifting into neutral to coast).

I'm suspecting the IAC servo of being faulty, but is there any way to test it before i start tearing apart the TB? I tried disconnecting it and I don't know whether the problem stopped because it went away like it usually does, or if it was the IAC being disconnected. It's hard to test without taking the car out for a drive, as it's not at operating temp right now.

Thanks
-Ross

Before you go tearing apart the ISC motor, tried the Idle position Switch.

I had a problem with mine but it would idle high not low, but I think it wouldn't hurt to check.

Can be checked with engine off.
In the idle position you should be reading 0-1.2 ohms from electrical conection of the idle position switch to ground.
If there is no change when throtle is open adjust Idle pisition Switch.
If there is a change in the reading but dosen't return to 0-1.2 ohms when throtle is closed then replace Idle Position Switch.

The switch can be found here
http://members.shaw.ca/dsm.1000q/Engineprimer/idleswitch.htm

good luck.

I'm not being facetious. Technically I'm a points and condenser not a DSM guy, but could your problem be related to the 'backfire' problem in your other post of today?

I'm thinking the explosion from the backfire is going to also travel up the pipe in front of the CAT, as you describe it, tajing with it freash air and may wack some sensor up there that has something to do with the idle/mixture or blasting a flap closed or something like that.

I may be way off base but it's a thought and both problems are occurring during deceleration.

Cheers Tony