The Bucking 47Cj2a

Happy Sunday Jeepers.
Just wanted to pick some minds. I have a 47cj2a, converted to 12Volt. Has been running and driving great. Untill the other day, I got in to run to the grocery store, and she was bucking like a prized bull through all 3 gears, with quite a bit of backfiring as well. I know the air/fuel ratio is right on so messing with that has helped none. It's in terrible need of a new muffler, my question being....could the muffler be so backed up and clogged it's choking itself out? Fuel is pumping from pump to carb beautifully. Could it be a carb issue, even though in neutral and just reving it up it does wonderful. Only in gear am I having issues. Timing in distributor off? Any input would be greatly appreciated!! It's getting warmer and she's my daily sometimes in the summer month's!! Thanks again.

Pull the spark plugs and clean them good, check your points to be sure they are clean and regap them if needed.
Does it run better with the choke out a little ?

Thank you guys very much
@48Willy's....it def runs better with the choke out a little.
@Dan and @Adrian......going to check all of that. Thanks guys. I have a new condenser and points as well as they're a bit pitted.
I have a buddy who still seems to thinks it's a carb issue from years of ethanol, but I'm not buying it.

could be a worn key/switch. I had to replace mine a while back. Barely touch the key and it would shut off.