Injector cleaner or you have a bad injector happened to me changed it out and been running perfect ever since. Same thing happened with marks car at countyline and me and emil fixed it in like 10 min lol. Best way to tell if its one of the injectors is either take a socket extension and put one end on the injector and other end to your ear or while the car is running unplug each injector until you find one that makes no change in the idle.