1996 xj 4.0 ho random misfire but runs xlnt?

My 96 xj with 4.0 and auto has 121k it runs excellent, starts perfectly idles smoothly has recent complete tune up with new cam and crank sensors. New fuel pump, good fuel pressure, no vacum leaks and no stuck pcv. Motor is stock except a KN filter in stock box, Modded stock distributor (with no excess play or wear) so I could adjust timing and Magna flow exhaust. This has been an ongoing issue and is very "random," it throws PO300 and always specific codes for different cylinders, but never the same ones for specfic cylinders. It is impossible to detect on driveability. You can't feel it miss when the light comes on, it doesn't stall or hesitate and hauls ass up every hill you point it at. It starts perfectly and idles smoothly, I have run a lot of injector cleaner with no changes or improvements I am truly stumped. The light will usually come on in a decellerating condition I live at the 5k foot mark in elevation and it usually comes on around the 3k foot mark when I am headed to work in the morning. Could it be a bad computer, air sensor? or is anybody aware of a TSB on the computer requiring a re-flash? any suggestions? I could change the coil I guess but you cant feel it stumble so that would just be tossing more money out in my opinion any ideas??? Let me know if you know!