I know you've checked out your wiring but it still seems like the most likely cause of the problem you describe. Have you checked the harness at the fuel pump? Your dash lights are on when it dies?

When I had a similar problem it was caused by the wires on the capacitor and lc filter being so old the insulation was cracked. I would start with the wires near the coil and wiggle where they meet the main harness circled in the picture. Ignition module, lc filter and capacitor would be my first spots to check.
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1990 LWB RS A/T
1990 LWB Base A/T
1991 LWB LS A/T Going...Going...