I have a 71 Mustang with a 351C-4V, an EDL 2665 intake manifold and a Holley 1850 carb. I am only getting about 7 miles per gallon. The intake manifold pressure is only about 12 pounds which is the only problem I can find. I checked the compression on all eight cylinders and it is about 155 pounds with only a few pounds variation. I replaced the intake manifold gasket and checked all the vacuum connections and got no improvement in vacuum pressure. I also checked the timing and it is O.K. at 6 degrees BTC. The intake manifold and carb. were added by the former owner and the engine was rebuilt at the same time, about 1500 miles ago. I did notice that the ports on the EDL manifold are condiderable smaller than the intake ports on the head (about three/eights of an inch in each direction). This seemed strange but a speed shop guy said this was probably just the way the manifold worked. Any ideas on what my problem is?