When i press the brake peddle on my t-bird it's really soft and travels very far, and barley slows the car down. I took it in to a auto shop and they said to replace the master cylinder, drums,shoes,wheel cylinders, rotors and pads, i did all that and it did not fix the problem. I had a lifetime warranty on my master cylinder so i went to murrays to get another one, put it on, bled the brakes and they are still the same. I was thinking it's the brake booster or proportioning valves but not sure. What are they two black things that screw on to my master cylinder before two of the brake lines, are these the proportioning valves.