Alright everyone I have a brain teaser I am needing some help with. I have an '01 XJ, cylinder head replaced in July, (thanks all for the help with that). Mid September a rough idle problem started to develop. For a little while once a day, at some point in the day, it would die at a stop sign or signal. But only once and then run fine. A few weeks ago a slight missing sound started It almost sounds like it is like it is choking. I changed the idle air control valve in May and already confirmed that the valve is not the problem. I have confirmed it is not a bad air filter and all the spark plugs are new as of July's cylinder head job. It sounds like it is not getting enough fuel or air. I am wondering if it might be the Throttle Position sensor or maybe the Ambient Air Temp sensor. Without having to replace each sensor as I go, any thoughts?