Vacuum fluctuates when brakes applied

Hey guys, got a weird one here, just installed new dual power booster with master cylinder. Brake only travels 1/2 down and stops rock solid with vacuum connected and when I disconnect the vacuum, brake pedal travels all the way down like it should. Also, my vacuum dramatically fluctuates when brakes are applied. I lose 3-5� of vacuum when I apply brakes and 8-10� of vacuum when brakes released. Any ideas? I drained out the air in the lines.
Author: admin