Vapor lock or not?

Ok, here's my problem. '71 Duster with a 383, 727TF stock 4bbl intake and Summit 600 carb. Ran great when I took it to Good-Guys in Des Moines a few weeks ago. Now it will start fine when cold but at temp the fuel will start to disappear from the clear plastic filter then it dies. Happens on the road or idling in the garage.

The filter is new, so is the fuel pump, and hoses. Dropped the tank cleaned it out and replaced the pickup/sender unit. Also put 'Cool Tube' on the fuel line from the carb to the pump then from the pump past the header collector.

Once it dies it's tough to restart, usually take 20 minutes of waiting with the hood up to cool things off, then it will restart. Timing is at spec, nothing has changed since the show other than I added a flex fan and shroud and put the electric fan on a manual switch (electronics kept failing). The only part thats not insulated is rail for the dual feed carb.

Out of ideas.
Thanks!