When braking while moving (at any speed), the brake pedal begins braking at its normal pressure point and then sinks to the floor with reduced braking effect. sunnyvale lincoln has checked the whole system for leaks and bled some very tiny air bubbles out of the abs control module. the problem returned after about four days. they replaced the hcu lines because some very minor "wetness" was found at the connectors and bled the abs control module again. the problem returned again after about four days. we have done three cycles of the bleeding now and this fixes the problem, but only for four days. sunnyvale lincoln is currently trying to further diagnose the problem. the navigator only has 32,000 miles on it and has only been serviced by the dealer. i am afraid to drive it until the problem is permanently resolved. these symptoms sound very similar to the f-150 brake investigation. the navigator uses the f-150 brake system.