I have a 2001 jeep Cherokee xj with the 4.0L straight six with just under 300,000 miles. I have had continuous cylinder misfire problems over the last 8 months or so. I have replaced spark plugs, coil rail, battery and cables, cleaned the IAC, and most recently replaced the fuel injectors with the Bosch 4 hole ones. Since I've replaced the injectors I've thrown a new code for Bank 1 system too lean along with a cylinder misfire code. My gas mileage is noticeably worse with the new injectors and I get a strong fuel smell on the drivers side of the car plus an occasional quick sputter when I accelerate at speed. But my engine idle sounds and feels much better than with the old injectors. I'm guessing I have some sort of issue with fuel system or exhaust but I don't know what, would appreciate any advice I could get.

 

Did you replace the O2 sensors?

 

If you want my opinion, replace the 02 sensors, then run a bottle of Mr Gasket "Cataclean" thru it. It made a BIG difference with my WJ. Works a lot better than Seafoam and cleans the cats out as well.

 

I have not replaced the O2 sensors because the computer hasn't thrown a code for them. Figured it would give me some sort-of exhaust leak/ O2 sensor code if that is the problem. I guess I'll look into that next.