02's are known for having bad outside tranny shifter solenoids ( I know I always mess up the REAL name for this critter). Anway it's on the outside of the tranny, driver's side. Cost is about $150 and takes about 15-20 minutes to change out. Main thing is to put tranny in neutral (key out of ignition), emergency brake on, then take old one off. Put new one on, align shifter, plug in, and then give her a go. The other thing that can also have an affect on the shifting is the Go-pedal(about $100 and 5 minutes). Replace those 2 items and if you still are having trouble, it's tranny time.