Does all of the functions jerk or just some of them?
I could not find the specs on your machine but I suspect it uses a load sense control system. If the load sense line is partially plugged or the pump control is hanging up slightly it would cause your system to respond sluggishly and potentially jerk.
Leak at the pump inlet would allow air to enter the system which would make the pump very noisy and could also cause the system to be jerky or spongy.