350 small block, horrible gas milage

[71C10Guy]

I have a 71 C10 pick up, which has an almost stock motor, just a cam with slightly longer duration and an edlebrock 650 carb, possibly rebuilt, but I'm pretty sure it's new ( my dad bought it at AutoZone).
Anyways the truck constantly reeks of gasoline, but only when not running (not a hole in the gas tank), and has trouble going over 70 miles per hour. I took my friend on a 30 minute drive yesterday on a full tank of gas and had to stop at a gas station on our way back because I had an 8th of the tank left. Basically, unless my fuel gauge was inaccurate, I got around 2 miles per gallon. The hoses and external fuel pump (gen 2 block) are dry, so I don't think the gas is coming out of them. The truck isn't missing as far as I can tell but has a rough idle, ehich can be fixed by adjusting the idle screws.

Has anyone experienced this or know of anything that could be causing this? I'm tired of driving from college to home and spending enough to fly my entire family on the same trip.
Thank you,
Mark