Could be the tank is not vented, try removing the gas cap when it acts up, if it instantly gets better you know what it was. With a helper you can even remove the cap while driving.

A collapsing fuel line sounds like a good reason too.

"knob" on the side of the distributor should be a grease cup to grease the shaft.

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-