draining gas tank...

car is still stumbling and backfiring under part throttle. there are no codes coming up. I'm starting to wonder if there's not something in the gas tank. There is a little oil around the intake, looks like the intake might be leaking a little so I'm going to have to fix that. A buddy thinks that maybe the fpr is going bad, i pulled the vac line (with the engine off, should it be running?) to see if i could smell fuel in the vac, negative. i was told that a fpr that was bad would put fuel in the vac line.
so, other than running it dry, is there a way to drain the tank that don't require me to get a mouthful of gas?

because it seems to be worse as the tank gets closer to empty.

Id like to pull some of the fuel out of it, catch it in a jar and see if it separates to see if i have more water (or whatever) in the tank than a bottle of gas dry can handle.
If its not a fuel problem what could be causing it if no codes are showing?