you are going too slow for that gear your engine has very little torque at low rpm
you may not be at a high enough rpm
The car is attempting to find the next gear, stopping the car while finding it, and then moving on.
change the map sensor
Poor driver or bad transmission.
your car must be stuck in a low gear and not able to switch out
it jerks because if it is automatic it is goin down a gear
If would not be bad for a car engine to shift from third to second gear if you are traveling at 30mph.
Check the mounting of the gear box, because the mounting of the gear box is like shock absorb.
That would be the second gear of your automatic transmission.
If the automatic transmission car jerks when accelerating and the dash does not indicate a gear, there is a problem with the transmission. Check the shift solenoid.
What kind of car is is? When it jerk while shutting off, do you turn the key off and it sits there chugging for a second before stopping?