IAC controls the idle.
Associated problems often without setting codes or Malfunction Indicator Lamp (MIL) are:
-Inconsistent idle or low stumbling idle, causing a stall condition. Difficulty in starting and having to apply gas pedal to get car running.
So before you buy a new Delco IAC - Why not try to clean it and the ports first and see if that helps !

If your IAC is still a factory install and the two Phillips screws have never been removed before, note they have thread lock on em and are in there real tight.
Knowing this, the first time I broke my two screws loose ..IAC Screws that is...To eliminate possibly stripping the Phillips heads... I used a....
1/4 " Ratchet with small extension, & socket to fit a tight proper fitting Phillips bit.
(I also used electrical tape from bit to socket to ensure no movement & not to fall out)
I manged with inwards pressure on the ratchet, to break my screws Loose!! Without causing any damage to the screw heads!
Mine were like welded in there! So "heads" up when you try to break em free!

The first photo shows the IAC Location on my 3800 and many IAC'* pretty much look alike as far as the IAC shaped base is concerned.
Remove the electrical connector and consider spraying the two screws with a penetrating oil first. I sprayed mine twice one day, well before attempting removal.



Now the with IAC off & in Soak mode, U will see that photo later....
Here is a view of what it may look like with tough carbon inside !



Even though Throttle body spray is recommend especially for Teflon coated areas, it just was not strong enough for getting this gunk out.
So I also had a spray can of good ole regular CARB cleaner handy.
The Carb cleaner worked so much better and with a few applications of spray and going around in circles with Q-Tips/ lint free shop towels, made it clean as a whistle!



Here was my IAC upright in spray cap utilized, allowing the IAC Pintle to Soak well, while I was doing the port cleaning as above.
(a 2 oz shot glass works well too) to hold the IAC while it soaks, and can be reused for later ...



Final cleaning of the IAC Pintle (spring thing) Consisted of using an old tooth brush (not mine LOL) and a bit of fine scrubbing.
Compressed air from a Portable "Dust Off" computer can was used, to dry & blow out any particles, before IAC was installed again.
The two screws and o-ring also got attention before re-installation.



I consider the IAC Cleaning as normal tune up /maintenance now once per year!
With The Clean IAC now installed, the car'* idle is now not wandering, like it was before.



Now I can celebrate ....