My car has a dirty stock 48mm TB. The car will run smooth somtimes and real rough at other times, it only runs rough at idle or when it's in gear and I'm sitting at a red light. I also have to hold my foot on the gas and brake when I race because otherwise the car bogs and has terrible throttle response. Otherwise the car runs perfect, I can floor it at any speed and it just roars. Could this have somthing to do with a gunked up TB? I heard that it could be a dirty IAC. If it is my IAC how should I clean it?

Remove your throttle body and spray it down with carb cleaner, it's pretty simple. You should get a replacement gasket from gm while you're at it.

How do I clean my IAC, I don't want to sound stupid but what does it stand for and where is it located exactly?

Not sure how accurate this is but it is step by step...

http://www.geocities.com/jgkov/IACService.html

Im kinda having the same prob...sometimes the car runs very sweet(even though it needs a ton of work) other times it bogs down, backfires, and generaly runs very bad. I just got done cleaning the TB( complete tear down) and porting the Phelum(think thats spelled right:P) and have yet to run the car..(still needs a new starter ) any suggestions on what else might cause this?
Thanks

I cleaned my IAC 1 week ago and boy does the car Idle smooth now I used to have rough Idle and stalling problems.

You may find it hard to get to so you might have to remove the alternator bracket etc.

Once you unscrew the IAC you can unscrew the pintle out. I was told that if you can unscrew it, it means that it is bad but it unscrewed easily and car is running great now. Anyway once you decompress the spring and unscrew the pintle I used carby cleaner to get all the dirt and grease off the pintle thread and anything else that was dirty and I could get too.

Put it back in and had to readjust Idle and TPS also as it was out of whack. Funny thing when I cleaned the IAC teh car did not start as Idle was too low. The IAC must have been jammed or somethingand was not working properly. I set Idle again and TPS and everything is sweet as.

Mike

how long since your last tune up? sounds like the same thing mine did when I roasted a plug wire on the header