Okay, so.. I'll be the first to admit, I know jack all about diagnosing problems with brake hydraulics. I've had my Miata since September, and in December the brake calipers in the front would stick intermittently. No big deal, it never lasted more than a couple minutes until last month. I needed to replace the pads anyway, so I took the time and took the calipers off to inspect them. The boots around the pistons were torn, so I removed the pistons cleaned the junk from around them and reassembled. I drove it for a while, and parked it with no issues. Well, tonight, I go to drive it on a nice little 5 mile round trip to the gas station. By the time I made it home, they were sticking so bad that the rotors were red hot, and the pads were LITERALLY on fire. I have no idea what's causing this. The brakes were bled and reservoir filled properly after I took them apart, and they worked fine for a couple of weeks, like I said.