I posted under this before. I am still having the same problem. I have a low and because it is low it is a rough idle. I noticed the trans is not shifting properly when I am taking it easy from a stop light. I am wondering now that I have changed the plugs and wires cap and rotor, air filter and fuel filter, plus had the fuel system flushed out why I still have a low idle. Check light reads the same Fail Fuel 44 and I still smell unburnt fuel comming from the exhuast. The charging system reads properly using an volt meter and the fuel pressure is also the way it should be. When the idle drops the lights dim until I press the acclerator to bring the idle back up. I don't want to spend unnecessary money on changing this and that. I changed the trans fluid and filter. Any suggestions.

 

o2 sensor comes to mind as a possible fault. Also I don't recall if the xj6 has one but on land rovers the IAC could be a possible fault as well with the idle symptoms.