93 with the 3.3 Tranny problems

The transmission was fine. My girlfriend drove the car to a city about an hour away and she parked the car. Said it did fine the way over there. She came out, started the car put it in drive and it acted like it didnt want to go into drive she said. She finally gets the car home, and it works fine for a couple days. Then reverse goes out completley, and Neutral is drive, and drive is drive. It can be in drive and down shift manually and the car doesnt downshift. This is an automatic transmission by the way. A few weeks later, the car works fine again. Then, yet again reverse goes, and now when you take off the whole front end shakes like crazy, and makes a loud noise. It finally catches and takes off. Its shifting at random points now. You are driving at 20 and it will shift to second and then down to first. I have had it to 3 people and they all say different things. I have heard, Valves, Clutch Pack, Torque Converter Clutch, and a lot of other things. Anyone have any clues as to what this may be? The transmission fluid smells burnt, however, the transmission fluid wouldnt cause eratci shifting and cause these problems would it?
The car has about 150k miles on it, nothing has ever been serviced except the ECM and the Rear Right Wheel Cylinder.
I have recently had the ECM replaced, and from my understanding, my specific transmission does not have any electrical parts in it short of the Lock up Switch.

Thanks in advance.
James