Hi Bean!
I guess It could still be having clogged filter problems. The gas tank definitely has a lot of rust. I thought I had run enough thru it to stabilize the situation, but maybe not. I put a coarse screen billet filter right out of the tank before the fuel pump, next is a Holley blue 97gph rotor/vane type pump, then about 25' of fuel line to the rear engine compartment. Once it gets there it goes thru the factory cartridge/bowl type filter, then thru the fuel regulator and into a standard cannister type inline filter. Next is the fuel pressure gauge (which I can only read while stopped of course) to verify Im still getting 6lbs of pressure going into the carb. All the filters are fairly large, between 2 1/2 to 3" dai. but historically it can clog a big inline filter in a matter of miles. The symptoms are similar to what I have been dealing with since I got the old beast. Your diagnosis is 100% accurate what I found before I rebuilt everything. Maybe the original problem -the junk fuel tank, is still fouling up everything. It was cleaned out 7 or 8 years ago, but looks pretty bad inside again.. I'm thinking Id rather just have a new one fabricated out of aluminum than continue fighting it. Damn frustrating!!