Mitsubishi Repair: automatic transmission, shift linkage, good shape

Question
Lately my car has been jerking when upshifting while driving. Sometimes it will get stuck in first or second gear. I just got the transmission fluid changed about two weeks ago. What could be wrong with it? Its only a 2001 model, the car should still be in good shape.

Answer
Maurice,
You should first check to see if your drivetrain warranty could still be honored by your local dealership.  If your car is not shifting, it could be a shift linkage or a bad solenoid that controls the shifting for your transmission.  You'll defintitely want a professional to inspect your transmission.  
Good luck!