1999 Pontiac Firebird Car will not stay running

It's bolted to the side of the throttle body assembly.

You fell victim to a common problem. Diagnostic fault codes never say to replace parts or that they're bad. They only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. In this case, this is the same part that Chrysler uses and failure of it is extremely rare. You're much more likely to find a cut wire going to it or a stretched or corroded terminal in its connector.

Now that you have the new part already, go ahead and try it, but there's only about a fifty percent chance it will solve the idle speed problem.

Here is a pic of the throttle body assembly. I have already looked all over it and have yet to find it.

Photo didn't show up. I do all my editing of photos and adding arrows and such in an MS Word document, then I copy it to MS Paint so I can save it as a jpeg file.

Is this the part you're looking for?

Yes

That has to be buried on the throttle body assembly somewhere. Be aware the two screws that hold it in are usually glued in with Thread Locker. Be sure the screwdriver bit you're using fits perfectly so you don't round them out.

If you can't find the part, stop at a repair shop and have a mechanic find it and point it out to you. There are line drawings in service manuals and online too, but those don't help when you already know the right area to look in.

Lol. I am a mechanic. I just figured out today that my 3800 is series II So I have to change the entire throttle body. But thank you for trying to help.

Dandy. I knew there were some that were different, but I thought all GMs used this unit. Happy you solved the mystery.