I have a 99 camaro. V6 just had it in the shop they replaced my MAF and "cleaned" my throttle body. Now I get it back and in an idle coast my rpm jumps from like 800 to 1k then back down to 800. While sitting still idles fine. While driving rpms don't jump. Just at an idle coast. Any thoughts?

 

You have a 4th Gen Camaro, and posted in the 5th Gen forum, so I'll move it to a more appropriate forum, to increase your chances of getting help.

The 1999 3.8L V6 has a “drive by wire” throttle system….. all electronics from the pedal to the throttle body, no traditional cable. The electronics control the throttle blade movements based on input from the pedal, idle control from PCM, the cruise control, and possibly even traction control (if vehicle is equipped). This is a very complex system, and relies on dual throttle position sensors, and the blade position servo in the the throttle body.

My guess would be the “shop” either screwed up something electronic when they “cleaned” it, somehow jammed the throttle blade movement, or the didn’t fully connect the harness connectors. First step would be to address with the “shop”.