One problem related to other fuel system pump has been reported for the 1999 Mercury Mystique. The most recently reported issues are listed below.
I recently bought a 1999 Mercury Mystique. At 68,900 miles the fuel pump on the car failed. I was in the process of getting it fixed and my mechanic showed me the old fuel pump after he'd removed it from the car. The ground wire was basically fused to the side of the plastic which my mechanic assured me should not be the case. I was told that it could have caused an explosion at any time. I will be lodging a formal complaint with the Ford/Mercury company as well but I thought that anyone else who owns a car of this type should know about this danger as well.