Just got my SerIII back on the road in September (after 5 years in the garage) and so far it's been running pretty well. It is a 2.25 gas with a 1950s Rochester, K&N filter, and a Crane ignition. About 2 weeks ago I started getting a few backfires out the exhaust and an intermitent hesitation in the engine (I now think these might be little backfires), mainly when I let off on the gas. It has gotten a bit worse and a few times the truck has stalled while sitting at a light/sign. I had some new bits around so I replaced the in-line gas filter, cap, rotor, and wires...no change. I have been thinking I need to rebuild the carb or sort-out the fuel pump in some way.
Last night I had a thought...perhaps the intake manifold bolt and/or carb-fixing bolts could be loose? I will check that issue tomorrow.

Any thoughts on whether I'm on the right track or missed something important?
TIA