It is not the slides, If you live a road salt area and do not wash the chassis very often the pistons will stick. Just replace rear disc calipers on a 2001 Expedition. I am surprise you could not detect it before it got that hot. You should have felt the affected sticking caliper during a low speed application of the brake.

 

My 04 was one of the first off the assembly line, and I still have all 4 stock calipers at 97k miles. And thats with heavy 35s for the last 10k as well.

 

May not be your caliper that is the problem, especially since you have changed it 4 times or so.....

The rubber brake line to the caliper is most likely your problem, sometimes the inner hose is defective or worn out and will colapse internally and not let the caliper bleed off properly....have seen this many times before on other vehicles....

 

it was definetely the calipers because they have been problem free since they have been replaced. I plan on doing the hoses in the next few weeks just for safe keeping however

 

Mine were replaced at 25K, after 3 sets of rotors they determined they where sticking. After 72K my rotors are starting to warp again, more than likely just ware and tare on them.