Does any one with a weber 32/36 use a fuel regulator? my engine sputters above 2500

ok, heres the deal, i just put my freshly body dropped truck together, rebuild motor (again) with a 32/36 weber, cam, header, right around 2500 rpm and above it hesitates just like it feels when in fuel filter is bad the more gas you give it the worse it hesitates. i am running a fuel pressure regulator. i set it to 3.5 psi like the directions said but it runs better when its on 5 psi (as high as it goes) just wondering if you guys use a regulator or if anyone had this same problem. all the vacumm lines are plugged. give me any ides. im willing to try it all to get this thing running good again. the filter is new the fuel lines are new all of the wires from the ignition switch to the plugs are new including the 220 dollar distributor. and the intake manifold was baked and cleaned, the only thing i can think of is that this regulator isnt working right and keeping the gas back too much. thanks guys. i'll have pics up as soon as i get them. -jim