Is there something "safe" to use to clean any carbon build-up off the pintle of the IAC valve? Gumout? Brake parts cleaner? Also, what if I cannot set the pintle to 28mm. I mean it doesn't move. Does that mean a bad IAC valve?

The IAC is a stepper motor. You can sometimes turn the shaft and get them to go back in but often not .

Clean it with some Throttle body or carb cleaner.

I never bother to set the length, I just run it in plenty far and have never had problems with them resetting.

I usually hook it up and let the ecm run it in. I have don't several post on how to have the ecm do it for you.
Here is one.
https://www.fiero.nl/forum/Forum2/HTML/073281.html

down a ways.

look at the spring behind the pental, if there is a groove in the head of the pental that the spring ingages, that is a "turn in" type, pull the spring away from the head so it's not in the groove anymore and turn the head to make it go in.\
if the spring does not fit in to a groove then that is a "wiggle in" type, just wiggle the head back and forth while give it pressure to push it back in.

and i dont set it to any measurement either, just in as far as it will go.

Yea,use some throttle body or carb cleaner on the tip but Dont submerge in cleaning fluid.

Am I mistaken but do you have to use a "sensor safe" throttle body cleaner?

Thanks everybody! Got the tip of the pintle (easy there) cleaned and adjusted and IAC valve reinstalled.
Sorry for the second grade humor.