Fuel Fluke

http://www.recarbco.com/technical/newtrouble.html#Warm_drive

I found this in a google search, don't know how much it will help if any, but maybe may spark an idea or 2.

I don't see "bubbles in fuel filter" or "fuel pressure drops suddenly" LOL!

I've checked bowl level while the motor is running... front and back.

Can the mechanical fuel pump get to hot and cause vapor lock? It's the warmest part of the entire fuel system from tank to carb.

The only thing I know to do is get rubber hose stick in a gas can and hook it straight to the fuel pump. That would eliminate the tank, and fuel line.