I just had my passenger side front brakes lock up. I took it to the shop and they replaced the caliper on that side and the pads and rotors on both sides. I then drove 1700k miles and no problem. One day the right front locked up again and was smoking. After letting it sit for several hours it was fine and it hasn't done it for about 2 weeks. I went offroading today and we were going up and down a lot of hills. We stopped and I saw my brakes again were smoking but not on the passenger side this time but the drivers side. We let it cool down for a bit, but after we got going again my brakes went almost completely out (i could touch the peddle to the floor. After getting out of where we were and not touching my brake peddle for a good hour I had brakes back and they were working fine. So why are my calipers lighting up and why did I loose all my brakes but got them back? Could the locked caliper have heated up the brake fluid making the brakes not work? Is my maser cylinder going out? Also the Bronco has been idling high, could this added braking stress had an effect?