[81MC]

I can’t quite tell from the video - but it was running but incredibly poorly?

It’s not likely a fuel pump. Electric pumps tend to work or not, it would be very odd to be kind of. Likewise with the filter, they tend to have a bypass so even a clogged filter won’t prevent enough fuel flow for idle.

Check spark at each cylinder - quickest way (thought technically in sure it’s. It recommended in that motor) is with a spark plug tester.

It sounds to me like you likely have either:
Messed up timing due to a bad crankshaft sensor, or
Corrosion at an ECU harness or grounding cable.

A bad ground can play all sorts of havoc. If there isn’t a check engine light on, that’s a pretty good indicator there is an electrical issue beyond a bass sensor. Inspect your ground point from the batter and ECU if you can find it, and check all your harness connections.