FWIW my MPI has passed the FSM checks

onto the MPI supply wiring ..

Good, the relay itself isn't high on my list of failing items. I find it more likely that a grounding, system voltage, or ECU damage is the underlying issue.

Since it sounds like reproducing the failure is easy I'd watch the main power to the relay and the signal from the ECU to activate the relay. Make sure the system voltage stays above 12v and that the pin from the ECU stays close to ground while the engine is running.

Make sure none of the ECU capacitors have leaked.

I was having this issue, was the ecu

ecu looks mostly decent, some of the protective coating is failing. i have a spare ecu. car now starts and runs, of course, in typical DSM fashion

might just swap the ecu, i think it might be in need of service

How have I never thought to use the female spade connectors as guides for the probe on the volt meter. You taught me a new skill today