I have a 2003 Buick Rendezvous just replaced transmission which is working well now but after transmission warms up when it tries to shift it slipped and then jerks in all gears
Well, you could take it back to the person who did the work?
I would hope your transmission is still under warranty. In the meantime check the transmission fluid level.
Please tell me that you didn't just purchase an exchange transmission and that you installed it yourself.