I have a 1997 A4. When I brake, just before coming to a complete stop, the brake pedalpulsates. In other words the brake pedal "kicks back up" with a sound of griding brake.I know its not worn brake pads because they are new.Anyone have an idea of what it is. ABS sensor? Wantto find out to see if its something I canchange myself b/f I bring it to a mechanic. Thanks for your help!