I have replaced my entire brake system from front to back and now have stock power front disc with drums on the back. When I apply the brakes the fronts will not release. I opened the caliper bleeder and it releases. So it is not the calipers. I cracked the lines on both sides of the metering valve and the proportioning valve and each one relieves the pressure on the wheels. So that rules out the valves. I cracked it at the master and that relieved the pressure, so thinking that maybe it was the master I replaced it, however no change. I then loosened the master from the booster and that did not make a difference. I checked the booster push rod and it is adjusted all the way in. So in my mind either the booster rod is incorrect or there is something mechanical in the pedal system that is not pulling back. Any thoughts. Thanks.