Brakes

Next time it acts up, stop on a slight incline, shift to neutral, place a block about six inches downhill of one tire so you will not look funny chasing after the truck, then crawl underneath and open the bleeder screw for the caliper that is getting hot. If that lets it release, suspect the rubber flex hose. There is a bracket crimped around the center of the hose. See if you can pry that open a little with a large Channel Lock pliers or a flat-blade screwdriver. Rust builds up inside that crimp and constrict the hose. You can force brake fluid through that restriction with foot pressure, but the fluid cannot release easily. When this gets bad enough, the brake pedal will be unusually high and hard.