So I started to really think about what was going on here and I just remembered in the "Hot Rod to the rescue"section that a guy with a truck had a cold crank issue (Greg says he had to “crank it forever” to get the truck started ) with a 502hp ZZ502 big-block crate motor.....well after re-reading the last statement stood out and it was...(Im not saying you are wrong at all about your grounding) but a good read non the less................
4. Improper electrical grounds: “EFI systems don’t work properly if the grounds don’t go back to the battery’s Negative post.” Sensors operate under minute voltage variations, so any voltage fluctuations, resistance, or drop can introduce erroneous readings. Remember, the circuit’s ground-side is part of the total circuit length, and hence, contributes to resistance and voltage drop. A standard chassis-ground won’t cut it.
.....at the end of the read was the top 4 EFI mistakes this was one.......here is the link to the article.......................
http://www.hotrod.com/how-to/engine/...over-internet/
.....I hope this shines a light on something we are not seeing...Rod Im sorry for your family's lost at this time........God speed and good luck......