Hey all,
I have an '82 with CIS, 159K miles that is slow to return to normal idle when I come to a stop and push in the clutch. Sometimes it gets back to 900RPM but other times it stops at 1300-1400RPM. I trick it into going lower by engaging the clutch slightly to give the engine a load; it does the trick down to about 1000RPM. It only is slow to return to idle when warm. First few shifts in the morning are fine; quick to return to idle, no lag. Here's what I've done so far to try and fix it:

Dissasembled accelerator cable, lubed it well. With cable off, I turned on the engine and revved it up manually (it was warm). The problem persists. Not the cable binding, I take it.

Checked to see that the microswitch is firmly clicking on and off when accelerator engaged; all seems fine there.

Used throttle valve spray on throttle valve. I undid the black plastic cowling below the throttle body to do this; noticed a slight tear where the metal band holds it to the throttle body. Doesn't seem to let air in, but hard to see in there. Maybe this could be the cause? I felt around up into the throttle body and it seemed clear. The butterfly valve seemingly moves unimpeded...

Put that all back together and started her up; no change. Still slow return to idle.

There don't seem to be vacuum leaks. I was told that vacuum leaks would lead to stalling, and this car NEVER stalls... so.... I don't think there are leaks?

Where do I go from here?

I read in a couple of archived posts on Brickboard that people had found the culprit in the idle air valve. I'm not sure where this is on my car. Can anyone tell me how to find this, or what it looks like / what it's next to? If I can find it, I'll try tapping it with the butt of a screwdriver, as some have recommended here before. Any other suggestions?

Thanks,
Matt