1992 Plymouth Voyager Help!

Here is my problem On sunday Jan. 5th I wsa driving my van when I noticed that my braked were beginning to smell like they werwe burning, at that point I was unable to get up to speed without flooring it. I was going 40 mph but my rpm's were over 4500. When I finally got stopped the brakes were smoking and the car was over heating. I had it towed home. The tow tuck driver who is also a mechanic. He seemed to think my passanger side caliper was stuc closed and causing the whell not to turn maikng it hard for the vechile to go. I had the caliper replaced and it ran fine for about six hours then it did it again. Only this time I noticed the brakes on the passanger side wrwe smoking bad and smelling bad plus I again overheated even though my temperature gauge showed only slightly above normal. HELP!