I'm using an Auto X-ray for OBD-II. It doesn't do a perfect job but does read most sensors on the move. The fly in the ointment is this: When it goes through the initial scan it says the O2 sensors and heaters are okay, but, I get no actual readings from the sensors? It also shows bank 1 & 2 as -100%. My guess is the two things go hand in hand? I had an EGR code before but no issues after tube and valve replacement. I do get an occasional code 171 and 174, bank 1&2 lean. It will go two weeks or more before those codes set. I do have a new DPFE coming. As I mentioned before, I have no issues with engine power or actual operation. The reason I ask about the timing, is the very low values I see. I would expect a much higher value under cruise conditions and light load. My comparison is a 3800 Buick engine, 1990 vintage. Similar crank fired ignition and waste spark coil setup. The one difference is the Buick uses a knock sensor where the 4.0 appears to not. My conjecture is Ford is using a safe timing map which is not conducive to decent mileage, but to keep everything happy under all conditions the truck may be used in, since it has no knock sensing. The Buick shows upper 40's to 50 ish degrees under light load and mid twenties at full load. I know it is a sort of apples and oranges comparison, but I would expect more timing lead with EGR flowing and moderate manifold vacuum, which leads to relatively slow combustion. I have had this vehicle since new, and it has never done well in the mileage category. I chalked this up to the nature of a 4x4 which has a small factory lift with the big tire option, but this has got me to thinking? Disregarding the cruise readings, even the initial timing at idle is very different. The Buick shows 20 degrees at hot idle in neutral which increases by two degrees or so when dropped in gear to help pick up the load. As the weather cools, timing increases two to four degrees in response to cool inlet temps. I know the 3800 Buick is much closer to the 3.8 Ford V6 in design, not the 4.0. The thrust of my initial question is to determine if I have a defect in the PCM or is this normal? Thnks for listening.