Brakes 1998 Expedition

I have a 1998 Ford Expedition ,Eddie Bower edition, 5.4 engine , 4WD. My problem is the left front brake does not release completely and I get the burning brake smell and the hub of the wheel gets hot, however the vehicle does not pull to the left at any speed, and this does not happen all the time. The first time this happened I had the Calipers,rotors, pads and rubber brake line replaced. This worked for several months it happened again and this mechanic found that the caliper slides were not replaced and he replaced the slides. Now again several months later the same thing happened and I had the rotor caliper assembly and pads replaced yesterday and today after a 30 mile run it happened again. WHAT DO I DO???