Running rough

[C101971]

So I'm getting kind of clueless with this problem. My truck, 71 GMC c15 with a 350, runs super rough out of nowhere for no reason, at first I thought it was a spark issue, I replaced the distributor, plug wires and plugs. It ran great for a few seconds then rough again. Fuel maybe? So I checked my fuel filter, it is glass so I can see if there is no fuel, and sure enough, a lack of fuel. Bought a factory replacement and she ran great for a few days then back to square 1. Replaced all fuel lines, filter seems fine, it is a mechanical fuel plump and it seems to work fine, I don't see why it would break after a few days.

I moved on to see if the fuel sending unit gas line was clogged and it's clear. No vaccume leaks that I am aware of, the carb isn't even a year old, the new Holley street demon. Never had to tinker with it. Jets seem to work fine. I've replaced the whole fuel line and I'm completely lost.

The engine is timed, 8° past top dead centre. Harmonic balancer is a bit wobbly but I doubt that would cause the issue.

Any ideas? I just want my truck to work again...