1988 Jaguar XJ6 starts but very rough idle /missing

I have an '88, but I've never had your problem even after sitting for 5 years. Does yours have the hydraulic rear suspension that still works. I had to change mine to the new strut system. Anyway, onward.
It sounds like you have covered all the bases. My only question would be with the injectors. The fuel filter will filter down to 4 microns which is about the size of dust. If any of this got past the filter it could have lodged in the injectors. Does it "lean cough" back into the air cleaner? This is an indication of a lean fuel mixture to one or more cylinders. You will hear a pop, pop, pop and a stumble on acceleration. You mentioned you cleaned the injectors. How? I have never found a "miracle in a can" that would solve this problem. I had to locate the faulty injector and replace it. Secondly, are you sure this new problem is fuel? Ignition or a gross vacumm leak could cause the same symtoms. Hope this helps. Jim at jamesweizel@yahoo. Com