2011 silverado first started shifting hard into first gear. Next issue started idling at 2000 rpms. Replaced throttle body off my 2008 Tahoe problem appeared to go away. Purchased used throttle body and installed relearned computer idle intermittently went high then normal. Hard shift went away until recently now throwing error code for trans and shifting into neutral. The problems seem to be intermittent and different issues not same one constantly. Been working on this going on about a week. Does anybody know or has had any related issues or a direction to go now would appreciate any help. Wanted to possibly reset pcm since it seems to be a computer related issue.