2001 Dodge Truck Front brakes running hot

I have removed and cleaned all the rust from the calipers and frame so the pads are free. The front brakes still run hot under normal driving conditions. (Not much city driving) It's a Michigan rig so rust is a problem and I noticed the caliper pistons were quite rusty but not leaking, boots in good shape, and pistons retracted with a c-clamp at the reinstall part. After a short drive to town, taking wife to airport I could smell brake and rotors were running hot. Q could the calipers be malfuctioning because of rust on the pistion. Q-2 could the issue be in the master cyl?
Other sugestions.