Like the title says my xj has developed a rough idle not like its misfiring but more like it is cammed out, just a bit lumpy i can feel it in the truck. idle is right around 900rpm on tach and does not fluctuate on the tach. did full tune up and ran injector cleaner. its a bit better but still there. any ideas ?

 

when was the last time a tune up was done?

assuming somewhat recently, you could pull the IAC and clean it. cleaning the throttle body isn't a bad idea either but def start wit the IAC it's easier than pulling the TB.

Here's a vid on how to do the IAC. It's a Wrangler in the vid but still a 4.0L.

 

You didn't change the spark plugs recently did you? I once forgot to plug in the wire for one of the cylinders. Ignition, everything was shaking like crazy and sounded like a very large, angry Volvo.