I’m curious in what you find.
I’m having a similar problem where my 390 dies after getting hot…after a 10 mile drive, just seemed to die quickly after a few sputters while on highway. Mine starts back up after 30 seconds or so after 5 sec or so of cranking. I thought mine may be a venting problem as well (seemed to be a vacuum in tank after removing cap), although I noticed I had fuel in fuel bowl via clear bowl window on my newer Holley 2 barrel.
I went ahead and replaced with a new G40 stant cap from eBay, and replaced existing Pertronix setup with new igniter II and Flamethrower II coil. Ran fine after a quick 5 mile test..trying this weekend for a longer highway run.
