Brake Foundation Components problems of the 2000 Lincoln Town Car

Brake pedal will fade out and not hold, consumer has to pump brake to get vehicle to stop, took vehicle to dealer and the master cylinder was replaced however, the same day problem reoccurred, while on the highway consumer stepped on brakes and pedal went to the floor, consumer had to pump brakes again. Consumer states brakes needs to be pumped while driving on the highway, consumer was informed by a Ford specialist that the fade was normal for this vehicle,also the mass airflow sensor was replaced, the windshield wipers/washers were replaced,the windshield was also replaced, and the engine head gaskets were replaced.