High Idle when truck warms up

[18 inch Crappie]

2000 Silverado just started to run at 1100 rpm when towing at a stop or in N, but when I shut the truck off and restart it runs fine for awhile and asks up again? A Sensor? UPDATE does it when not pulling the boat also. Just did it this morning.

[Scott K]

I would bring it in and scan it for codes. I would suspect an Idle air control (IAC), or a throttle postion sensor (TPS). Or just a possible vacuum leak.

[Jeremy airjer W]

I was kinda of thinking IAC myself. They are pretty rare on newer vehicles. It probably wouldn't hurt to clean the throttle body first. These are notorious for dirty throttle body and sticky throttle plates.

[18 inch Crappie]

How do you clean the TB ? I pulled the IAV out and it was covered in black soot, I cleaned it off and moved the plunger in and out and reinstalled it. It took a couple minutes for the engine to run right at idle, then test drove it and seems fine but I did not let it warm up at all. I will drive it around Thursday and see if it acts up.