funny fuel problem,need suggestions

[blazer2007]

80 chev truck stock 350/350 with headers ,performer intake and 4106 edelbrock carb. Everything new in the last 5 yrs. It,s starting to get warm here 32 degrees Celsius about 90 F. Here,s what happens, start truck in the morning,let it warm up abit and go and a minute or 2 of driving it runs out gas . Sometimes you can catch it and pump the gas while driving if not I put in neutral and start it right up no problems, no pumping just click vroom . Then it,s fine all day. It seems to do it from warming up to before full operating temp. After that is fine. Did this a couple tears ago for abit . It doesn,t do it every day but when all the conditions are right it does it but what conditions I don,t know. I,m thinking some sorta vapor lock or low idle mix, gas cap ? Single line to gas tank if that means anything