If the Jerking of the car happens only when you apply the brakes and stop it could simply be bad brakes or bad brake calipers that need replaced.
It can also sometimes be an indication of a failing transmission if the vehicle continues to Jerk when stopping but it's hard to tell exactly unless I was actually driving the vehicle and can feel where the Jerking is coming from.
I would have the brakes checked out as well as the transmission and go to a mechanic and let the mechanic test drive the vehicle so they can see and feel exactly what is going on.
If your brakes are good and the car continues to jerk when stopping then it's almost always an indicator of a failing transmission but could also be a bad transmission mount as well.
If the transmission and brakes are not the problem then it could also be A dirty or failing idle air control valve.
When the engine RPM drops below the normal range of about 800 RPM this often times will cause a Jerking feeling of the vehicle and may even cause the engine to stall completely.