Fuel problems

So I have put NGK plugs in Beldin wires, rotor button and DIZZY cap fuel filter so what else could be causing poor MLG. the truck does not smoke, I even raised the bed and replaced two fuel lines so Im really lost now, Could ignition coil or distributor cause bad mlg it runs smooth as can be but drinks gas like 10 to 12 miles per gallon so what could be the problem.

Cusser verified that the fuel pump could be leaking fuel into the oil through the mounting plate on the head. There is a hole on the side of the fuel pump that if oil leaks out of it it means the fuel pump is bad.