Just put a brand new Sorenson IAC valve in my 88' Camaro. Car is idling at ~2250 rpm now. TPS is .54vdc. Idle adjustment screw is backed all the way off the butterflies. Timing hasn't changed since this morning. HELP!!! Thanks guys.

You must resett the ECM after you've changed IAC, this is how you do it :

1.) Start the car, let it run for 5 sec. Shut it off.
2.) Let it be off for about 10 sec.
3.) Start the car again and see if it runs good again

and if that dosent work remove the negative battery cable for 20 secs and start over from 1 again.. this shall help it to relearn..

Unfortunately I've already done all that. I hope that the previous owner didn't have the car rigged somehow to compensate for a bad IAC.

ADJUSTING MINIMUM AIR:

Procedure I followed:

Jump ports A and B on the ALDL.
Turn on Ignition, Wait 30 seconds.
Unplug IAC.
Start Engine.

This is where I run into the problem. Instead of being able to adjust the RPMs down to 450, The lowest I can get them is 1500. The idle speed screw is still backed all the way out, to where the butterflies won't even come back far enough to meet it.

Is it possible that the IAC isn't working? Maybe it's letting too much air through and keeping the engine at high rpms?

Update:

after some carb cleaner and some spirited driving, the idle came back down. I was able to properly set the minimum air. One thing though, will anyone's car hold idle at 450 rpm as the guide suggests? mine sure won't. maybe because it's not stock anymore.

get a scanner and check the IAC steps at Idle. hot motor they should be 10-20 (I run at almost 0-5 helps with floating idle speed). Also was the pintle length checked before IAC install should be at 1.125" from end to the gasket face. Did you disconnect the spark advance wire when checking 450 idle?

The guide didn't say to disconnect the advance wire. I've gotta find a laptop with a serial port and make myself an ALDL cable, that'll help me figure some more things out. The IAC adjusts itself to where it should be, shouldn't need to make any measurments or adjustments other than making sure the pintle is pushed into the housing far enough so it doesn't get damaged during install. Am I mistaken?

My car idles around 450 but sometimes it will stall at a red light but not very often.

This is too low, hard on oil pressure and alternator volts, 550 RPM is a better number when driving.

The 450 RPM is only used in stock setups, when setting minimum air flow at the throttle body.