I have a 2003 Bonneville SLE with about 150000 miles. When it is hot it starts idling high pushing the RPMs up to over 2000 w/o touching the gas pedal and begins to shift very hard. This only happens when it is HOT! I have replaced the throttle POS sensor, Manifold Pressure (MAP) Sensor, Coolant Temperature Sensor and flushed the radiator. I have also replaced the PCV. I know I should replace the MAF but it pretty pricey and I am unemployed at the moment.(I did bypass it as I read about and it did not fix the problem) Also pulled the EPC valve and compared it to a new one and see or feel no difference in the spring back. Was thinking it may also be the transmission solenoid. But I don't know much about it. Anyone have ideas?
Thank you all

Do a thorough check for vacuum leaks.

I have. I have even pulled lines off to see if it made any changes. Im not saying that I have checked every single line as I don't know know where every single one of them are located.
something to add, Before the problem started, I would notice my transmission dip stick popped out from time to time. So this would lead me to think about a vacuum issue. Do you know of any vacuum lines that would connect to the transmission or that would cause build up to push the dip stick out?

sounds separate to me no vacuum connected to trans anymore. you pull the iac and clean it and the tb?

Just went and looked at this part on line. that was the first thing that I changed.
Thought I had listed it in my thread question but I see that I failed to do so.
Sorry.

Do you know the history of the upper and lower gaskets? I'm wondering if the mating surfaces are opening up when they get hot causing a leak.

you clean the gunk in the tb out when you replaced the IAC?

I did clean the TB. But did not pull it off to clean it. (so I would call it a half aced job)
Do you think I should pull it completely off?

At Mike1995-Im not sure I am clear on what gaskets you are referring too?

Sorry I am really no where near being a gearhead, not from lack of trying to understand mechanics.

I just noticed that i put EPC valve when I meant to say EGR Valve. All these acronyms get confusing.

Ok, it sounds like you haven't did anything with the upper and lower gaskets. The bottom ones tend to be real trouble makers.

We have quite an extensive How To section for the 3800 engines. Here is a link for the how to for the lower intake gaskets.
https://www.gmforum.com/mechanical-1...gasket-278911/