anyone good with carburetors?

[Invigor]

i've got a 1987 dodge ram van with a 318 2bbl holley carb, it idles fine, but runs very very very rich (like $20 fuel in 3 days, city driving about 20minutes a day). exhaust smells like a skidoo's..

i've so far replaced the choke vacuum pull off, that didn't help. would it be recommended to take it apart and check the float, needle and seat? if it's choke related, how do I go about it?

I ran it home today with the engine cover off, air cleaner box off, and just the bare carb exposed so I could watch it..when I was driving at about 50kmph and stomp on it, it backfires, once it even backfired off two pistons.

i've checked vacuum lines, but there are only about 3 and they all seem to be ok.

can anyone recommend anything?

thank you!