What is causing a misfire on #4 even after new spark plugs and new coil? on 2003 Jeep Liberty

engine light came on when i turned a/c on. After coil on #4 was changed, and the code reset, it seemed to have fixed the rough idle. I turned the a/c on while driving, the car jerked a little and the engine light came back on. And it still reads misfire on #4

Asked by for the 2003 Jeep Liberty