New Mexico

Hello, I have a 2013 GMC Sierra Sle 1500 4x4. when the truck is warm, it fires up nicely and runs ok. Just around 1200 rpms as I drive. Too high of idle but not bad. Once I put in park after reaching 210 degrees, it revs up to 3000 RPM's!!! Then once I restart the truck, immediately to 3000 RPM's! Next morning, it will start up and warm up fine, once it goes into park or key turned off, the problem begins. This is what Ive done so far: 1.Cleaned throttle body nicely 2.New air intake sensor 3.Took the proper measures to have the computer re-learn 4. Even disconnected the battery multiple times. New throttle body? Why would it stay open when vehicle is at operating range. Any help would be greatly appreciated.