2000 Buick Century Transmission Problem

I have a Buick Century Custom. My problem is this.

Sometimes the Transmission jerks when changing gears. On take off it will sit there and vibrate if you hit the gas to hard instead of spinning freely. I read a message on you site from someone else that had the same problem. He had the transmission rebuilt and it still is doing it. He said someone told him it could be the Computer I was wondering what you think on the matter!

Thank you for you time.