i have a 90 t bird 3.8 v6 and im having problems with my car. its shurrtering real bad when i drive it. i have recently had a lot of gas mileage decrease. the shuttering has started to get worse. sometimes it well jerk real hard as if its gonna cut off. if i hammer on it then it doesnt do n e thing. some people i know tha twork at a frod dealer ship said it was a tune up. did that and it still did it. i was told by more peopel it could be the torqure converter or the caddialac converter. but my exhaust system is all one peice from the engine to the tail pipe. does anyone have a idea what could be causing my car to do this. thkz alot.