I had a similar situation . Mine was due to an old brake hose from frame to rear end . It would allow brake fluid to go to wheel cylinders but would not allow fluid to return back . This is quite common . I was able to verify this . When the brakes were not released I cracked a bleeder and could here the shoes retract. New hose , no problem. Note : Do this test in a safe location and the vehicle is secure and will not roll as you release the brakes .
Another way to test this is to drive without using your brakes . I know this can be difficult and may not be possible . Check to see if any drive . If not possible put the truck on safe jackstands . Rotate the wheels and check for drag. If no drag vigorously apply brakes . Now go back and check to see if your brakes are releasing . Try to rotate the wheels. If wheels are dragging crack a bleeder . See if this improves the situation.
It could be something different but if you have new wheels cylinders I doubt whether it is them.
