There is a shock absorbed inside the tongue that should take that jerky feeling out. Your shock might be bad or your master cylinder is empty and your brakes are not working at all and letting the tongue slide all the way back when you come to a stop and then it pulls all the way forward when you take off again and this will feel jerky. Maybe you should describe jerky when being pulled. Are you saying while you are pulling it down the road a 60 mph and it is jerky???? If that is it, then all I have said at first is out the window.