I have a 2002 xj8 which started running rough, I replaced the plugs, cleaned the mas air flow sensor and replaced the vacuum line going to the brake booster. After driving a few miles the restricted performance light comes on and the car starts running rough. I disconnected each coil 1 at a time and noticed a difference in idle so I guessing the coils are ok. Some of the codes that are showing are PO171, PO301,PO304,P0300,P1313. Any info would be greatly appreciated. Thanks

 

Duffman - I've moved your post from the General Tech Section to the XJ (X308) section where members with the same model can best assist you


regards,
steve

 

Misfires are usually coils not plugs. Lean code likely due to misfire.

Check fuel trims to make sure not an actual air leak.