Trans problem

I need some help here. I have a 95 stratus 3.5l the trans dont want to shift out of 1st at times and feels like it wants to down shift when on the highway. the check engine light is on but only comes on after driving for a few minutes and some times comes on as soon you put in drive . the car also feels like it stumbles from stop sign to stop sign. ANY IDEALS????:banghead:

Anybody???