One problem related to crankcase (pcv) has been reported for the 1999 Ford Expedition. The most recently reported issues are listed below.
The contact stated while driving vehicle experienced sudden acceleration. When depressing the brakes the rmps revved very high. When lifting foot off the brakes the vehicle accelerated. He eventually depressed the brakes hard enough so that the vehicle stopped. The cruise control was not in use. He took his vehicle to the dealer. They told him that the pcv had a leak in the vacuum system. The vehicle is now being repaired.