Believe it or not, here is the answer: The engine that the rebuilder sent was an AJ-28 for an S type and not the AJ-27 needed for a XJ8. When the engine was delivered, I had called the supplier to discuss the fact that the timing cover and oil pan was different. They told me that I could just swap the oil pan and timing cover because the 4.0 liter V-8 was modular. That was correct to a point, but the reluctor for the rear of the intake camshaft that measures cam position for the ECM is different. The attached photo shows the 5 fingers of the AJ-28 intake cam and the 4 of the AJ-27. I changed the cams, installing those from the original AJ-27 and all the problems went away.