What else could it be?

[chevyfan420]

Originally Posted by chevychic

but finally I took it up some hills and got it doing it really good, then got out and checked the underside of my air cleaner and sure enough, there was gas dripping off of it and some sitting on the edge of the carb air horn.

So at least I have a little more to go off of now.

I dont think backfiring will acually blow raw fuel onto the air cleaner. I've seen black soot on the lid, but not raw fuel. Perhaps over-fueling is part of the problem. You said you reset the float level, but did you clean or replace the needle and seat? Also, what type of carb are you running?
If you had a collapsed lifter, then i believe it should pop through the carb constantly.
If you pull your dipstick, wipe the oil on your fingers, and look closely at it under a light for little "shiny's"

Good luck, Jim