about three weeks i had changed the rear brakes on my f150 4x4. after the job was done i bled the rear brakes because i changed the wheel cylinders...now after the truck sits for any amount of time and put it into drive the brakes seem as if they are locked up and i am doing a power stall. after applying gas to get it to go forward two loud pops are heard from front passenger and driver side as if the calipers are locked up. my question is there anything that has to be done to bleed the proportioning valve or metering valve to fix this?