The car is not shifting the way it should.

What is your question?

I started out the car cut off coming in the driveway. I replace the fuel filter and changed the oil. I changed the spark plugs, the ignition coil pack and the modual underneath. I could drive the car a bout 15miles with no problems but once it heated up it started acting up so I changed the O2 sensor and the transmission fuild and filter. It was still acting the same so I changed the catilac converter. Now it is worse what am I doing wrong