Popping Exhaust/Backfire and stalling while offroading

[chevychic]

Hey all,

Been driving my truck again for the past week. It's got a brand new front-end on it and new tires on the rear.
It's been sitting for about a year now and it definitely needs a tuneup.

Some of you may remember that a little over a year ago, my 2nd tranny blew out so I had the original tranny and t-case rebuilt and the torque converter replaced. After I got the truck back I noticed that I'd get a popping/backfire out the exhaust under acceleration. It was usually under medium to heavy acceleration and would happen the worst just before the tranny shifted. After shift, the sound would go away. I also have what sounds like an exhaust leak under normal driving.
This weekend I plan to take a look at the plugs...the wires are relatively new...maybe 10,000 miles old, as well as the dizzy/caps/rotor/etc....I'll check them anyways since with all this moisture we've been having here in Oregon (surprised we're not underwater by now) and sitting for about a year, I'm thinking it's likely my cap and rotor need to be replaced. I'm also going to check my timing. I really don't see why my idle mix would be off as it was fine before and no one has messed with it that I'm aware of.
Is there anything else I should pay special attention to to locate the cause of the popping?
Is it possible that a different stall torque converter create this problem?
Or could my exhaust leak create this?

About the stalling while offroad....it's usually when I just tear through the bumps and ruts without taking it nice and easy...who wants to go nice and easy when you're playing in the mud anyways??....After going over about 3 - 5 good bumps/ruts, it'll stall out...my guess is the float in my carb is too high so gas is sloshing out the top of the carb...this is indicated by the wetness and gas smell around the carb and manifold when I get out and check it...but will this cause it to stall since there should be enough gas in the bowl to keep the truck going for a little bit further, even if it's not much?
We're still dealing with a Quadrajet rebuilt 2 years or so.

Other than that, it's SO nice to be driving the beast again!!!