When I am braking slowly to a stop, just before coming to a complete stop, the ABS feels like it is kicking in, and the pedal goes almostto the floor. Otherwise, the brakes work normally, other than the pedal does not seem to "pump up". Applying the brakes quickly works normally. I thought it might be caused by a rear brake adjuster not operating proplerly requiring excess fluid to apply the brakes, but I just had them replaced, and I still have the problem. The front brake pads and rotors are in great shape. I am wondering if it is a bad master cylinder that is allowing fluid to flow back while braking, but this does not explain why it only does it at a very low speed. Any ideas?