Evan, have you tried swapping to a different caliper on the brake that drags? What's supposed to happen when the pressure releases after a brake application is the square O ring that seals the fluid is also supposed to retract the piston a few thousandths when it returns to "square" after being distorted slightly when the brakes are applied. At times, I have had to do some serious honing of the caliper bore so the piston is a sloppy loose fit. Otherwise, the piston can't retract enough to keep the pads from dragging on the disc. Back when Ford was using plastic caliper pistons, it wasn't a question of IF, but WHEN the brakes would drag. I can't count the number of chrome plated metal caliper pistons I swapped out on early 1980's Ford brakes!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
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