One problem related to brake master cylinder has been reported for the 1999 Ford Taurus. The most recently reported issues are listed below.
Total brake system failure I was driving the vehicle at medium speed, and pressed the brakes to slow down at the curve. To my horror the brake pedal went down all the way without slowing the car at all. There was no brake warning light. The brakes came back briefly after pressing a few times, but went off again at the next stop light. The car ran through a red light, but fortunately there was no cross traffic. I pulled over slowing it down and put it into park. We got the car towed to the nearest brakes repair shop. The mechanic has informed us that the cause is an "internal leak in the master cylinder".