2003 Hyundai Santa Fe jerking problem

When driving it will start jerking and if you change gears (ex 2nd to 3rd or 4th) and give it more acceleration it will stop jerking. Sometimes when stopped or idling it will start jerking and if you don't give it more acceleration it will die and keep doing so until it is done with its jerking phase.
It was taken to a mechanic and they said that nothing came up when diagnostic testing was don't. No codes came up either as to why it was doing this. It does it anywhere from 4 -6 times a day depending on how much I drive. What could be causing it to do this? I have looked up on line threw a few different websites and it says that it could be the throttle position sensor. Could this be what needs to be replaced?