'93 tranny problems

I really need some good advice from some experts here. I drive my bird and feel as if when I get to the 2-3 level that my car is somewhat struggling to excel but, then sometimes it does it with ease. I took it to a tranny tech and he said that it feels as if my engine needs to be "adjusted" or "cleaned". It does have a minor leak. And when I get to to a stop light the car trembles and sometimes the "check engine" light goes on and then the car shuts off. Should I put my bird to rest or fix him?.
Please help me.

have the throttle body cleaned out, that`ll probably help the stalling & rough idle.