One problem related to gasoline engine has been reported for the 1999 Mercury Mystique. The most recently reported issues are listed below.
The car has been in the dealership service dept more than I seem to have it. . For many different problems. Needed a new engine at 23k,airconditioner broken at 24k,the car shakes and vibrates had it in the shop many times still shakes! rotors are pulsing again had them turned twice already,needs to go in this Aug for a peeling clearcoat correction on the passenger side 2 days to paint. . And the car only has 26k help! and Ford has ben terrible with dealing with problems and never provides loaners even when they had my car for 3 weeks!.