briefcase

Hey everyone, I'm having a hard time with a new purchase of mine: a 91 pickup, 4 cylinder 22re.

I was told by the previous owner that they thought it was idling high. Since there isn't any tachometer in my truck, I just installed one, and was a bit flabbergasted by just how high it was idling; it was sitting at around 2400-2500 rpm idle.

I turned the idle control screw all the way down till it bottomed out but the engine is still idling at around 1800 rpm. My first guess is that something somewhere is letting in way too much air, and so I'm making a list of things to check.

I read here
http://www.pirate4x4.com/forum/gener...sm-advice.html
that with your idle control scew all the way down that your engine basically shouldn't start/run. And they suggest to check the "auxiliary air valve" which I assume on my 22re means the idle air control valve attached to the throttle body.

So I'm looking at trying to do the following things:

Check for vacuum leaks using either the propane method or the aerosol method (suggestions for either method or what aerosol to use would be appreciated)
Check the IAC for proper functionality (not entirely sure how to do that just yet, but will find out through google I'm sure)
Check coolant hoses for obstructions running to and from the IAC. I assume draining all the coolant will be the best way to actually do this.
I'd like to check the timing but I don't currently have access to a timing light (I'm trying to find one to borrow, but it turns out that they're a smidge on the rare side)

I've already cleaned the throttle body and adjusted the TPS to be within spec. Initially the truck was throwing codes 41 and 43, however, since disconnecting the battery a couple of times it hasn't thrown any new codes my way. Obviously they've been cleared out, but no new ones are being generated as far as I can tell. I'll continually jump it to make sure. Does anyone know how long it would take the truck to throw a new code?

I'm wondering if you've got any other insight into what might be causing the issue, or if there's some other information that I should be looking for to further diagnose the issue. Thanks for any help you can give.