I would look at the Main and E-Brakes first. The Washer in the center on the Shoe should be loose enough to move with your fingers. You may be dragging a corner of the Linings and as you run it slowly heats up the Drum and you start dragging the whole Brake Lining. You certainly should register some sort of Drive Fault. The throw on these Brakes are in the .002 to .005 range.
