99 Escort with a rough idle

This phantom idle has been driving me and my mechanic nuts for the past 9 months.

So far, I've had it tuned up, had the spark plugs and wires replaced twice and we've sprayed carburetor cleaner on the vaccum hoses to see if a leak might be causing the idle and also tested the motor mounts by keeping the breaks on and pushing the gas a little to see if the engine raises. I've also ran some fuel injector cleaner through it. Nothing pans out.

It's rougher when the AC is on, but still noticably rough when it isn't. In addition, it's "almost" non-existant when the car is in park or nuetral... but it still idles a little hard.

If anyone has dealt with this phantom before and knows what it is, I'm all ears. I've had about 5 different mechanics look at it and they all disagree or are confused as to why it's doing it.

Thanks a bunch if anyone has any advice.

your IAC...Idle Air Controller

Is that a common problem with Escorts?

it seems to be, when it comes to idle problems...I've been told it's under $20 to buy the part and do it urself. I've yet to change mine, but my problem is related to valves. The IAC is directly on top of your throttle body,looks like a little black motor...Haynes manual, $11 at AutoZone, will help you a LOT.

It's rougher when the AC is on, but still noticably rough when it isn't. In addition, it's "almost" non-existant when the car is in park or nuetral... but it still idles a little hard.


I'm having the exact same problem with a '91 Escort. Have you tried changing the IAC? Did it fix your problem?

I also found this topic (http://www.automotiveforums.com/vbulletin/showthread.php?t=222772) where someone said spraying the IAC out with WD-40 worked for him.