Crank the truck and it will shift out fine for about a block then quits pulling turn it off let it cool for a minuite or 2 and crank it up and it will shift fine for another block then quit pulling

Hello, there is no way to know what the concern is by symptom alone. You'll need to do line pressure tests and use a diagnostic tool to check electronic function. https://repairpal.com/repair-shops/gmc-repair-and-service-in-arlington-texas