Rough cold idle with A/C on (IAB problem)?

[STRider]

When my 95 MTX is first started and the A/C is on, the idle is low and rough. It tries to idle around 500 RPM and seems to stumble a little, then it will jump up to 1,500 RPM. Trying to drive is a little difficult also. It acts like it is missing and is a little down on power. Once the car warms up, there are no problems. Also, if the A/C is off, the car idles fine, but still seems to have a slight miss until it is warm.

The car has done this for several months and I have changed the plugs (Motorcraft), plug wires (Motorcraft), replaced valve cover gasket and plug well seals, checked valve shim clearances and cleaned the intake. The spark plugs had normal wear and the back wells did have a lot of oil, but this was not the source of the problem because it did not have an effect on the cold idle problem.

I'm thinking the IAB valve needs to be cleaned better or replaced. I thought I cleaned it when I cleaned the intake, but it is possible I missed it. I just wanted to see if anyone else agrees with the IAB or if I should be checking something else.

 

[NiNeTy Fo SHO]

In my opinion, it wouldnt be a bad place to start. Autozone will test it for free telling you if its good or bad.

Check out this thread...
http://www.shoforum.com/showthread.php?t=37371

You can pull the codes to see if that tells you anything also...

 

[MilTownSHO]

Clean the IAB then reset the idle so the computer can relearn how to idle with maximum load.

Search idle reset procedure, it should come up!

 

[STRider]

Thanks for the reply. I forgot to mention that I have read the codes and I always get 111 for KOEO and KOER. I also pass the cylinder balance test but the car is always warm when doing these tests. I have also reset the idle a couple of different times. Other than this rough idle when cold and the A/C on, the car runs fine.