Still rough idle

still trying to fix my rough 4.0. It has a very rough idle, almost like the timing is missing. Could this be the problem and how can it be adjusted on an 89 XJ with a 4.0?
Greg

When's the last time you had the injectors cleaned. I had that problem on the wife's xj and I removed them and took them to a shop that cleaned all 6 of them using ultrasound( $12.50 ea) Ran great after that. Check your area for a shop that cleans diesel injectors they can do it, they even supplied the new orings. Or buy them for $50 apiece.

Those of us with 1990 or earlier XJs have an EGR on the engine. If it fails, it ususlly sticks open, which results in a low, rough idle. If your idle speed has also dropped, then check the EGR function. Try a search here for EGR for info. There are quite a few things can cause a lousy idle, in the ignition and fuel delivery systems, or sensors (like a shot oxygen sensor). Any more info?