1996 Ford Explorer brake pedal vibration and noise

Replaced the pads on all wheels, changed the master cylinder due to leak going into booster. Already bled the brakes 3 times. Now when you step on the brake pedal sometimes it vibrates under your foot and a wierd buzzing vibration sound can be heard seems to be coming from the booster area but not sure. Seemed to be braking fine when there wasn't the vibration, when it does vibrate the brake seems to drag or slip some. The more you drive the worse it seems to be getting, the buzzing vibration sound is staying constant even when not applying the brake. So we decided to resurface the rotors and reinsert the new brake pads. Now it is worse still have the vibrating foot pedal and noise, plus a strange grinding noise like the calipers aren't releasing from the rotor and steering wheel is a little shaky and a strange "clunk clunk" sound from somewhere underneath. My brother thinks its the booster as the mastercylinder was leaking bad and he thinks it leaked into the booster and messed up the diaphragm, but the pedal is near perfect as far as pressure goes.I'm leaning toward the ABS that hasn't been bled. Need a lot of help now. Thank you