351 Ford Motorsport Engine Dies

[cobrabuilderI]

Problem for your consideration if you could help me out friends:
Was running the snake along the West Coast of the Gulf of Mexico this Friday afternoon (Clearwater beach) and had run it for 30 min. or so. It konked out. I mean it was running fine, then the engine died. Sputtered for a bit then died. Pulled it into the parking lot of a rather seedy motel along the beach (had several lookers at the beast- "Wow you're lucky to have that!" was one) and checked the electrical which I knew wasn't it because all was running fine. water below 200f and oil p @70 so I knew engine was ok. Called a friend said it had to be no fuel. Turned fuel pump on manually engaged the carb so I could see fuel coming out and VARROOM. It cranked and ran. Was running back home, and it did the same thing as before after running 20 min. or so. Did the same thing as before. Turned fuel pump on, cranked carb till fuel, VAROOM tried to get home- 20 min later SAME THING. Almost got home and it did it again. Was able to get it home. Before I made it home where I stopped there were some guys that helped me out said I didn't need elec. fuel pump- they would run it without. Do you think that might be the problem or the fact that I put regular gas 87 oct. vs. 92 which is all it has known? It is a Ford Motorsport Engine straight from factory. Any insight my friends?