I hope by posting this it might help others in the future. First some history; I built my 85 XJS Jag with a yard pulled 89 Corvette L98 about 9 years ago. I’m combat disabled so I work slow and built my own harness that mirrored the Vette and tied it into the Jag main feeds. I had to have Vats burned off the prom but it ran great. About three years ago I bought a new 4 bolt main short block and new L98 alloy heads and at the time added new Ford injectors. The engine is stock with the exception of no cats and I used the old style Rams head exhaust manifolds. Shortly after the swap to the new engine I was having the typical “runs good when cold, but rough when warm” I tried every test and my Diacam never showed a code nor readings that were out of limits. This year I started fresh and since the FR was original I added a new diaphragm and ADJ. No improvement though and I started reading here again. Today was the day and I checked OHMs on each injector cold which were all around 14.6. Ran it till it started running like crap and checked them again. I was hoping for a low reading yet they all showed around 15.5. I then started the car up again and started pulling connectors one at a time as you would do with spark plugs. All but #3 showed a change. Being bank fired I checked the plug with the engine off and read battery voltage. Then I took a closer look at the #3 plug and decided to try a better contact by slightly bending the plugs contacts. Bingo that was the issue. I gave all 8 a bit of a spring and added Di-electric compound to each plug (sparingly) The Car runs as it should and all I can suggest is look at all connections when apart. Bottom line is the easy stuff is what screwed with my mind.