cut it off and absolutely refuses to restart,until.... (long)

I'll check the sensors, but since both of you said "ground wires", I think that may be the first place to start. The only thing about that is when I got the car, the grounding strap from the back of the head to the firewall was frayed, so I went out and got a huge new grounding strap and put it on. Are there other places I should check? There's no telling what little things were done during the engine swap by the previous owner. The motor itself isn't even a year old yet. I'd guess it probably has about 5000 miles on it. Thanks a million gents, I appreciate it.
Dave