Hey, I have a 1998 Mercury Mystique and about 4 months ago something happened with the way it switches gears. Now instead of switching at 3k rpms like before, it won't really switch until I let go and press the gas pedal again. Sometimes I have to hit the gas pedal and let go of it more than once for the gear to switch. So if I would just press on gas pedal and don't let go it will redline. Also sometimes it revs up without even the car going fast. And finally it will not switch to the last gear at all. When I am on the highway and going 70mph, it is at 4k rpm but should be at 2.5k. So with all of this I am getting just 14mpg in the city in a 4 cylinder car
So here is my question, could this be just because of some kind of sensor? Is there a way to adjust the transmission on a Mercury Mystique without actually changing it?