title edited , please keep them family friendly

[xconcepts]

So I just picked up a 78 C10 2 weeks ago. Test drove it, no problems. Now when I go over 45mph it surges/jumps heavily and seems as thou it is not getting fuel. I have to push in the clutch and try to rev the engine to keep it from dying. Sometimes it works sometimes it doesn't. When I press the gas she doesn't rev or get any fuel almost like its out of gas, but I know its not.

I've replaced the ignition mod, sparkplugs, cap and rotor coil and the fuel filter near the tanks. Not sure what else to check. I was told the fuel pump is only about 6 months old, but again it only does it at high loads over 45mph.

Its a 78 4 speed 350.