I have a 98 Mystique as well. Auto, 6cyl, 2.5 L. I have also noticed that I get a jerking motion, whern my car shifts from first to second gear...seems to happen after the car has been running for about 10-15 mins or after 15 - 20km. If I pop it in neutral and turn off the engine and then turn it back on, it corrects its self, well until another 10-15 mins or 15 - 20km have past.. I thought maybe it was a computer problem because it seems to stop when the car is first turned on, but I don't know for sure...any help would be helpful ...