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IAC issues? 2003 Ford Focus LX 2.0

Over the last week or so, my car has occasionally started very roughly. It stumbles and is very rough. After about 20 or so seconds, it smooths and drives fine.

Also, I’ve noticed in the last few weeks that there is a noticeable drop in power when I turn on the blower, even with the AC off. Not a loss as where it stalls, but still very noticeable. Then I’ve also noticed that when I’m at a long light, or other times I start it and it doesn’t stumble/start rough, that it will sort of feel as if someone is slowly pushing down on the accelerator and releasing, and this can go on for a while. Not dramatically, but definitely noticeable.

I suggest getting the battery and charging system tested.

2003 Ford Focus LX 2.0L
Which Engine ?
Is It An SVT 2.0L DOHC ?

According to Ford, some 2003 - 2004 Foci with this engine (SVT) can develop a rough idle, rolling idle, high idle, or induction backfire, mainly after a cold start, and some vehicles may also exhibit a hesitation or surge at steady cruise speed.

If this sounds like your engine and your symptoms then it could be caused by loose or mis-positioned rubber boots and boot clamps on the intake manifold. They need to be inspected for these conditions.

If they are loose or out of position then Ford recommends replacing the clamps (revised parts ?) and the fuel injector o-rings (fuel rail and injectors are removed as a unit). I’d obtain a copy of Ford TSB 07-10-7 for help or go to a dealer.

If the boots and clamps are ok then proceed with regular diagnostics.


Thanks for your help. It’s a SOHC, thanks for catching that, I meant to put it in my original post.

@jkn1027 clean your throttle body.
If that doesn’t fix your problem, I suggest replacing the IAC.
Your MIL isn’t on, is it?

Thanks for all the comments. I’m beginning to think it may have something to do with the throttle body/IAC.

DB, no lights came on.

Another thing that popped into my head that’s probably relevant. In early Nov. I cleaned the battery terminals and connections. The next morning as I was driving, it did seem to idle a little rough, and a CEL came on. I did take it to O’Reilly’s to pull the code, and darn I can’t remember what it was, but it did have to do with the idle. I drove it like that for a few days, no issues except it felt the idle was a bit rough. After about 3 days, I was driving and the light went off and the idle seemed to smooth out. I’m wondering if it’s a gunked up throttle body it could have taken the computer a longer time to re-learn? That’s a complete guess on my part of course.