brakes locked

Today i was driving in my woods and the jeep felt like the brakes were stuck on. so i took it down to the garage and filled up the tires (they had 0 psi) i figured they could have been making it feel resrictive. But that didnt fix it. i jacked up the front end unlocked the hubs and both sides are equally as restrictive (brakes are on a little bit).
So i pulled back the little boot on the master cylender and sprayed some pb in there. I worked the pedal a bit and it seemed to be fixed. i took it up the road to confirm and all was well. i went back in the woods and got a little stuck and it got very hot in the engine bay and the brakes got stuck again. leading me to beleive its heat related.
Before i tear it apart has anyone had this problem before? I should probrobly make a heat sheild for it. But im thinking i will flush out the old fluid and see what it does. Maby the old fluid has obsorbed water and is boiling building pressure an applying the brakes? Id rather not take it apart if i dont have to. I see herm has got a dual chamber kit for cheap thad be a good upgrade if it came down to it.

 

sounds heat related,and sounds like you are on the right track

 

Haven't had them lock on me. I did have one wheel cylinder stick and not work.

Sound like its time to take it apart and clean the rust off.