Heinz57

Moses - Thanks for the quick reply and ideas. I'll investigate them and let you know.

My son has a 2001 Cherokee Sport 4.0 liter. We are getting intermittent misfire codes. Initial misfire code was on cylinder #1. Engine starts and idles rough. When accelerating down the road, significant missing at 40mph and can't accelerate beyond that (engine light is also blinking). Sometimes it works itself out of it after turning it off/on. Other times, no rough idle and all runs well. First think I did was replace the throttle position sensor. No luck. I then replaced spark plugs and the coil rack. First code I got after that was misfire on cylinder #5. So, I put the old coil rack back on to see if the misfire would go back to cylinder #1. It ran fine for a week and then the cylinder #5 misfire and rough running at 40mph came up again with the rough running engine. It worked itself out again and has been driving fine for a week now. I saw the recent related posts, but our problem seems a bit different. Really puzzled. Any thoughts?