whats the engine vacuum?
is the vacuum line hooked up under the throttle blades..??
is the pushrod used, the correct one for that boooster..?
was the booster and master a matched set??
is the master a manual master.. ?
is the masters bore size correct for the calp. bore size..?
do you have a 4 w disc master..?
did you clean the rotors and pads.. or are they full of oil/grease?
my bet is lack of vacuum.