History of truck...It's a 1966 F100 with an early 70's 302 4bbl with a small block C6. Was not running when I got it, hadn't been driven in years. I Rebuilt the Holley 650, replaced the distributor with new,points one and new cap, rotor and plugs, replaced oil pump, replaced fuel pump and all rubber fuel lines, added in-line filter and cleaned fuel tank and all metal lines. Started up great and ran fine for the first couple of days. All of the sudden it began to act like it was starving for fuel after it the engine got warm. It would sputter for a short period and then die. It would start right back up so I don't think it's a vapor lock issue. Some times it only takes @ 5 minutes for this to happen, sometimes it can be driven for 15 - 20 minutes before it happens. The strangest part is, if driving it acts as though it's starving for fuel and sputtering and then all of the sudden it's running fine again. after it happens the first time it keeps coming and going. Any suggestions?

 

I don't know if this is the problem, but the needle and seat that the float controlled was not always made to withstand unleaded fuel and would swell and give the symptoms of an erratic float level or low float level because it shut off too soon.
Worth looking into, what do you think?

 

Thank you for the input, it certainly seems like a fuel issue but never considered this. I'll check it out. Thanks again.