Brake drags, wont release

I have a 93 F 150. Last weekend the RH front caliper locked up and wouldn't release. Changed the caliper, brake pads and hose to the caliper. It was fine foe a week and now yesterday it started draging again. Today it is fine. Is this a proportioning vavle problem??

Did you use hi-temp caliper grease when mounting the ones that float (non-stationary). Also make sure there's a little play between the brake pedal arm and the rod that goes through the firewall. W/o play, compensator sometimes restricts flow allowing pressure release. (Switching to synthetic fluid will cut lota future crap too)