I bought this car from a guy that let it set under a tree for 1 1/2 years with out being started. Naturally I have a new carb(in sig) and I have a clear fuel filter. It still has the Holley racing mechanical fuel pump on it that came with the car. The fuel psi stays at 7 psi most of the time. Once in al while it will read 4 psi and I have noticed some fuel delivery problems. The clear fuel filter stays approx 3/4 full of fuel except when fuel pressure drops. Then its about 1/3 full. Is this a fuel pump problem or maybe a vapor lock problem.