If I get into the gas hard and have to hit the brake pedal to slow down the pedal is very hard.The booster somehow has lost it's vacuum.At times under normal driving the pedal will be very hard and the car will only come to a slow stop.When GM put the vacuum brakes on the TTA's did they use a TTA specific check valve for the booster?I just can't get a good pedal since switching to vacuum brakes!!