Fluctuating idle

[MJRemi]

I can't seem to find an answer through Search. At idle, especially when cold, my engine idle ebbs and flows between 300-800 in approximately 3 second intervals. If I give a little gas and let off, it drops below 300 and stalls. This symptom improves as the engine warms up but does not go away completely.

I have a new EGR valve and fuel filter. What else can I check or replace to solve this annoying issue.

[JeffN]

Make sure your intake manifold is tight

[Boots]

Check ALL vaccume lines and try calibrating the TPS (throttle positioning sensor). Also check the IAC motor (idol air control)

 

That helped mine alot.

[shawn]

oxygen sensor- mines been doing that too and that was what was told to me.

[MJRemi]

OK, after supper ( = dinner ) I removed the IAC and saw it was coated with carbon. I cleaned the TB cavity with carb cleaner, ran to Autozone, bought new IAC ($60), drove back home, and installed new part. This seems to have greatly improved the symptoms. Now the fluctuation is very slight from 750-800 and disappeared once the engine warmed up on a 8 mile test run. I'll keep my eye on it for the next few days but if things persist, I'll check some of the other suggestions. Tomorrow I'll be installing drop shackles and a new steering wheel.