Hey, everyone. I have an '87 N/A. When the motor is idling, say just coasting down a street, and I step on the brakes, they grab fine the first time. After that, they don't grab very hard at all, and the pedal gets harder and harder. It's almost the same when you step on the pedal when the car is off. When the motor is revved up, the problem goes away. I tried searching and all I found was stuff related to brakes making the idle drop. Any suggestions please?

 

vacuum line may have a leak in it or yer brake booster is done for

 

check the check valve on the vacuum line to the booster, i would bet it has failed.