autozone is full of crap. evap control valve is small solinoid valve tucked into the corner of the engine compartment on the passenger side near the windshield. The part cost me ~$10 from a motorcraft distributor.
If the code persists, just replace it. It can be cleaned to squeeze more life from it, but when I decided to just replace it I wondered why I had bothered. (I also had code 1443 as I recall for that)
The idle air control valve is something entirely different and controls engine idle speed. You'll know when it's bad or needs cleaning when the engine won't idle unless you depress the gas pedal. This doesn't usually throw a code. At least it didn't in my case. I just cleaned it with throttle body cleaner and all was good.
ISC/IAC valve may cause various idle problems.
Symptom is it gets sticky and may cause hard cold or hot start or idle too high, too low, adjust idle too slow.. etc.
Most find that cleaning it only puts off the problem a while OR it changes the symptoms, - like from stalling to too high rpm.
That IS a good indicator, however, you need a new one. Another indicator of the failure prone nature of these is the cost and availability.... everyone carries 'em and they're relatively cheap.
this am , the light went out. i thought check eng light stays on until someone resets it. what gives?
No, what happens is if the car goes through a 'driving cycle' and the problem did not re-occur, the MIL is commanded off.
evap purge can be like that. Basically the solinoid is sticking. It got unstuck.
Buying a cheapass POC from AutoZone has the same effect as cleaning.
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