One problem related to brake sensor has been reported for the 1999 Ford Windstar. The most recently reported issues are listed below.
My battery has been dying due to bad sensors, when I did get it started it became stuck high revving ,the car accelerated and smashed into the curb in front of me, and the brakes wouldn't work so even when I stepped on the brakes to put in reverse the car went flying into the curb behind me, I finally got the vehicle to a complete stop by pulling up the emergency brake. Then I had the car towed to my house.