INTERMITTENT HARD BRAKE PEDAL INABILITY TO STOP THE CAR IN A SAFE MANNER. I HAD THE VACUUM BOOSTER PUMP REPLACED TWICE. ONCE THE REPAIR LASTED FOR A YEAR THEN THE LAST TIME THE INCIDENT REOCCURED AFTER THE SECOND REPAIR. THE FIRST TIME PRIOR TO REPAIR THERE WAS AN ACCIDENT TRAVELLING A 5 MPH AFTER THE FIRST REPAIR THERE WAS A HARD BRAKING INCIDENT THAT ALMOST CAUSED AN ACCIDENT AT AROUND 40 MPH. THEN HAD NEW BOOSTER PUMP REPAIRED. AFTER SECOND BOOSTER PUMP REPAIR THERE WAS ONOTHER HARD BRAKING PEDAL INCIDENT BUT WAS ABLE TO STOP THE VEHICLE WITH EXTREME DIFFICULTY. THE FIRST INCIDENT AT 5 MPH MY WIFE WAS DRIVING.