Alright, I hate to bother you guys, but I got a head-scratcher on my hands.

1991 Volvo 740 B230F Rex-I/Regina Ignition with Bendix ECU.
Replaced the timing belt about 500 miles ago.

I pulled this thing out of the woods a few days back because my main mail ride, a 1998 Jeep Cherokee, had a broken valve spring.
The old clunker did well for about 7 hard hours then decided she'd had enough of that mess and shut the engine off out of nowhere.

She's getting spark and the fuel pump hums on. I will be changing the fuel filter tomorrow. After troubleshooting it all day with the 7xx FAQ, it finally cranked for 30 seconds tonight, but but quickly died when I let off the accelerator. Anyhow, I suppose it could be somewhere in the seemingly sub-par Rex-I/Regina ignition system or in the fuel delivery, but it sure doesn't seem like it.

My next plan is to check the timing and crank sensor. Any ideas where to go from here, y'all? I checked the fuel ignition/pump relay and it is clicking on and off when I turn the ignition to accessory. And since I hear the fuel pump turn on (there is no secondary pump on this vehicle) I assume it's not the fuel pump relay/