72 Demon starts bogging sporadically once warm

AJ/FormS said
As you can see from the drawing, with the separator gone there is no other choice but capping or plugging.One vent should be enough.IIRC that 4-corner system was only a 1 or 2 year deal. I thought it was only found on E-bodies, but I guess I was wrong.
That line going to the front, dips down somewhere close to under the rear seat, and I have seen it rusted solidly shut there,from the inside, and so, not venting at all. Mine was only a 3/16 line

I’ve gotta do something to reroute that line to stop it from just draining fuel out though. I mean it’s a steady flow dumping out when I fill the car up.. I’m thinking running the line up to equal level as the filler neck somewhere to stop it from draining.
I’ll have to do some research on that other line coming out of the sending unit though to find it’s purpose.