I get jerking bang coming from the rear - misfires?

Hello,

First make sure you have correct level of transmission fluid. Many times when the fluid is low the transmission will have hard shift when its cold and can become smoother as it warms up.
Be sure to check the transmission fluid when the engine at operating temperature. You want to check the transmission fluid with the engine running in park.

If the level is good then you might have an issue with the shift solenoid.
Is your check engine light illuminated? Many times the transmission issue will trigger the engine light, which can point you to the right direction.

https://www.2carpros.com/articles/automatic-transmission-problems

I have attached transmission fluid check procedure as well as the shift solenoid diagrams for your reference.

Please let me know of any questions.

Thank you.