Mine does it, just like you describe. Feels almost like it could stall.
Also, when turning right. Blinker, slow down, coast, truck "super slows" rather than coast [ which is weird ], make turn coasting, truck gets confused and bump, clunk, choke and then lunge out, when gas applied. Hopefully explained that understandably / makes sense.
Googling yields this have been a problem for years before ours and folks are told " normal " gm tranny programming etc. Crying ass shame really on a 70k new truck. My 20 yr old toyota 4sp auto shifts and behaves better and more predictably. I really don't think gm gives AF.
Epilsonplus, where you located in southwest?