"It runs fine when I initially start it but as soon as it heats up ...."
you might be putting the wrong things together, might have nothing to do with "heat", but with length of time things are vibrating enough for a piece of junk to plug the tank outlet - check how long it takes a few different times, do it with the hood closed [hotter] and open [cooler] - also if it actually is vapor lock, putting some spring type wooden clothes pins on the line between the pump and carb should either eliminate the problem or make it take longer to happen
also be a good idea to make sure the pump is actually moving enough fuel, the amount initially in the carb bowl will let it idle normally for awhile, but the pump may not be keeping up - does the filter show a good flow right from startup? does the carb inlet needle open properly? if the carb isn't allowing fuel in, there won't be any flow
Bill
