Originally posted by Brad10071977:
Subject says it all. The Rpm surge a lot when it idles, and even stalls out sometimes. I tried cleaning the MAF but it wasn't very dirty anyhow, and it didn't fix anything. I will just replace IAC if I have to, but it's expensive and if I can just clean it, that would be better. Thank you in advance for any info.
This can be caused very easily by unmetered air (i.e. there's a hole somewhere after the MAF) entering the intake.
The effect gets stronger as the air temp gets colder.
(the injected fuel amount is calculated by the MAF info and the mixture gets too lean, causing slight rpm drops occasionally on idle, and larger drops on very small engine load (even power steering, braking)).
Of course sticking IAC is another possible reason.
The Haynes manual reasons that although Ford recommends against it, you cannot hurt the IAC any more by cleaning if it is already sick.
Tiv
