Pinched wire under the dash near the brake pedal assembly.
check the transmission mount for being bad.
A slipping belt or some kind of air flow problem..
you have air in the lines bleed the slave
the brakes or the emrgen see brakes
Brake rotors or drums need to be machined or replaced. If it causes steering wheel shaking, check front brakes. If happens when applying parking brake look to rear brake problem.
transmission shift bolt loose try pushing gear shifter all the way back to park
the brakes
ABS brakes are not spongy. If you have spongy brakes the reason is that there is air in the system. You need to have your brakes bled.
What_is_a_loud_humming_from_car_light_motor_after_in_lowers_down_and_closes_on_your_1997_firebird
Static Friction
Static Friction
your brakes are about to give out... you should go to wal-mart and have them replace them