I had an 04 silverado. Changed a dead battery and the exact same problem happened. It's related to the computer in some way. Loses it's mind if a battery isn't changed in an exact way. Dealer told me it was nothing to do with the computer, but when I got it back it was working perfect. Until the next battery change.

I also had gauge cluster issues that I repaired myself.

I also had an intermittent hard shift that appeared to be a tranny problem at first. Until I figured out shutting down the motor, opening and closing the door and restarting would make it go away from 4 hours to 4 days. Weirdest crap you've ever seen.

Otherwise it was a good truck.