2014 Silverado shifting / idle problem

[Bradysims2]

I have a 2014 High Country 5.3. With 54,000 miles Having a rough shifting / idle problem. As far as it shifting it’s always 1st -2nd or 2nd- 3rd gear. To me it almost feels like the transmission itself is shifting fine but feels like it is not shifting at the right times. It’s almost like when it shifts the motor and trans are not on the same page so to say. As far at the idle goes it seems to only idle weird after it gets hot from driving a while. It will idle at 500rpm then drop to 400rpm you can hear the throttle body click and it will bounce back up to 500. The problems I’m having make the truck Unbearable to drive in traffic. Every time I have to sit in traffic of any kind I swear I’m going to sell the thing. The only other problem I have with the truck is really clunky shifting from park to drive to reverse and down shifting. Park - drive “clunk” drive to reverse “clunk”. When I get hard on the breaks coming to a stop “clunk”. I have no idea if these problems are related or what they could be. I have had it to the dealer 2 times and a trans shop also. Everyone says it’s fine and in good working order. I call BS. If anyone has any idea what could be going on or any advice I would really appreciate it. Thanks