Along with other posters the only thing that comes to my mind are relays and their age.

Fuel pump and Lambda relays. The latter controls the frequency valve operation from the ECU and the 0-2 sensor output back to the ECU. Early AMM system if you throw in the air flap movement of the fuel distributor.
It is a two pole relay, that I think, is turned on with the ignition signal like the fuel pump relay.

On my 1978 GT, it is located on the driver’s fender, next to the headlight dipper relay. It is about an inch square. Age and corrosion made it as you say, flaky.

At first, it randomly started hard. Later it just would start run rough and then go fine. Once it quit on me, I got truly interested. I switched out the ballast resistor and the small black box on my car, which may be considered, the ICU today. It still did the hard start thing just as often.

In desperation, I studied the wiring and the fine printing on the diagrams. I investigated the ECU connections and relay functions. I notice a stray relay. I then noticed once while cranking or shortly afterwards that the frequency valve did not always buzz. It has to buzz!

It turns out to be that relay was the final fix. I put the ICU back and it has always worked fine and was the original. I left the newer ballast resistor were it was because it seemed to be a simple part. I think, they make them internal to ignition coils today or hide them better in the wiring.

Maybe I was lucky but thought I would pass it along with the idea to check your fuse panel. Look for corroded fuse terminals as that will cause dropouts on things, even more so with the newer cars.

Phil