The flathead in my 1947 Ford is having some trouble and I think I have narrowed it down to a fuel issue. The flathead has been rebuilt about 3000 miles ago. It is 59A that has been bored 60 over and stroked with a 4 inch Mercury crank. It has a mild cam and running on 12 volt. It has stock heads, intake, carb and fuel pump. The distributor has been rebuilt and the car rewired. The fuel line is rubber from the tank to the fuel pump and runs inside the frame. The problem is after about 20 minutes of driving the engines starts to hesitate. Then I lose rpm and speed. I can put it to the floor and it won't gain rpm. Also have tried to rev it up with the clutch in and it does not increase rpm. Then the engine will just die and not restart. I have checked the carb with the air cleaner off and when I hit the throttle I see it adding fuel. I have been thinking it is vapor locking and the pump is not able to pull fuel to the carb. I have removed both the inline fuel filters that were on the car. This is where I am at now. I would like some suggestions to aid in finding the problem.