Took to the dealer they told me the rotors needed to be turned. Had rotors turned but problem came back. Somedays the truck will do fine but other days it will lock up and if I turn the truck off and back on it may help. Not sure whats wrong. Explained to the dealer and left it for a week and they told me the problem I explained never occured. Not sure if its the Delta Stroke Sensor/Brake Booster or what.