Fuel Starvation / Mechanical Fuel Pump

Update:

I drove the car yesterday afternoon for about an hour, with the gas cap off. Equal mixed driving this time around (50% city/50% highway). The temperature was between 85 and 88 degrees w/ 70% humidity. The car didn't stall once. It did sputter one time, but I'm pretty sure it was due to my funky 700r4 shifting into OD prematurely and bottoming out the rpms.

The clear fuel filter didn't have much fuel in it, but apparently enough to keep it from stalling. I still intend to wrap the entire fuel line from where it's parallel with the header collector all the way to the carb. Extra insurance.

I'm concluding my tank isn't venting properly and I might have a moderate vapor lock issue that can be solved by further fuel line insulation. Hopefully I'm right or it's going to be a long 3,000 mile trip.