BlueJayXJ

so I just bought a 1998 Cherokee and so far the only problem I have been having is every once in awhile it will start almost bogging and jerking. I have heard that the TPS could cause this and the low idle, almost sounding like it wants to stall, but the guy I got it from said he replaced it and looks brand new. So my question is... what else can cause this to happen, how do I fix it, or do test the new tps and see if that is just a bad one from the factory? Thanks for all the help!