Fuel Pump seems to be the missing ingredient. A couple of times when the key was turned there was a buzzing (or rapid clicking) coming from the passenger side footwell. A gentle tap on the kick panel (where the ECU and FP controls live), and it started right up. Also of note, there was evidence of water intrusion. The floor pan carpeting is not soaked, but the pocket on the side of the passenger seat was. The headliner is dry (was replaced by previous owner), the seal (gasket) around the door opening is intact all around. (Yes, the window was closed). Maybe clogged sunroof drains? Maybe leaky windshield? We made a plastic "raincoat" for the (Ford) ECU. Any other thoughts or suggestions?

Thanks for the insight(s),
Andy
for reference: '91 745LSC ('91 Lincoln LSC Converse in-house swap)