Ok,

You have ruled out the system relay and it’s plug on socket for bad terminals.
It’s hard for a AMM to shut down a car but it can make it run lousy.

The hose behind can make it die if idling or stumble when taking off. Make sure the throttle switch is clicking from idle mode just as soon as the plate wiggles in the bore.
You cleaned the bore and it might be out of kilter just a enough to cause a transition issue from idle to power on pulling.
The fuel management system is a stickier for sudden unmetered Air ingress from excessive leakages. Checking all the vacuum hoses was a good idea.

The next thing that pops into my mind is the main fuel pump connections.

If it the original pump or definitely a non Bosch pump, may have corroded terminals or some loose/ jury rigged one’s on the fuel pump itself. Most of the time the original pump will be sprayed with undercoating somewhere on it.

As the pumps start getting really old they can pull extra current which can overheat the bullet terminals up inside the shroud.
You have to pull them out and make sure their clean and snap back in place, down inside, like a spark plug wire. I spread the splits a tiny bit.

The age comes in on these pumps as the brushes have worn a lot in 200,000 miles.
Are you anywhere near that mileage as I know the years are?

I just picked up a 1993 and I plan on eyeballing the pump closely from underneath for that condition.
It is not exhibiting any problems at all and it just passed it smog test well below the states average output of emissions.
The car was well taken care of but the struts are shot. This tells me it’s been bounced a lot or lots of pot holes in Nevada. Since was a bird watcher, I bet it saw some off road wear.
So inspecting under the car I will be doing very intently looking for brush rash!

Maybe talking more about the cars condition may raise up a clue for someone else?

Phil