I have a 2003 Jetta TDI. My rear brakes and sometimes one of the front brakes randomly lock up. I'm driving on the highway and suddenly feel either the car slowing down even when I accelerate, or the wabble that comes from hot rotors. The brake pedal feels hard at this point and the brakes are hyper responsive. I'm usually able to release the hardness in the pedal by pushing down and quickly releasing it. It happens even when I disable the ABS fuse AND I have now replaced every single part of the braking system (booster, check valve, master cylinder, calipers and hoses). Everybody so far is shaking their heads and has never seen something like this. What else is there that can influence the brake calipers so that they randomly lock down on me?