Glad it's working for you, for now. I still think it isn't vapor lock--with vapor lock, fuel flow is reduced or eliminated, and the car runs for a while on what's left in the float bowls, then starts sputtering and dies. If the engine is running fine and then dies suddenly, that's almost always electrical.
The fact that the problem is temperature-related makes me think it might be the coil or, if you have one, electronic igntion.
Once, while sorting out an apparent vapor-lock problem in my Bugeye Sprite, I replaced the fuel lines with clear tubing ad watched what was happening in the lines. Pretty impressive--the fuel looked like ginger ale, a large bubble formed in an upward arch in the line, and the plastic fuel filter looked empty. Yet, fuel was still getting through! I think that the fuel has enough pressure to get past large bubbles in the lines, but if a bubble gets trapped in a small area, like the carb float valve or fuel pump valves, the force on the bubble, at ~3 psi pressure, just isn't enough to dislodge it, so it blocks the flow.
It's not just ethanol. Fuel these days has a lot of high-volatility components to provide anti-knock properties and to minimize air pollution. We have to learn to live with foaming fuel. In the Bugeye, I reoriented the fuel lines so they were continually upward, and bubbles could then flow to the carbs and be vented through the carb vents. No more problems.