66 C10 292 Trouble I'm Stumped!

[junk4cash]

Hey guys. My 66 with a stock 292 is giving me some running issues. I'll try to make this short.

One day on the way home it started to bog in 2nd and 3rd gear. Hardly made it home unless I was in 1st gear. I checked fuel filters and all were good. Checked fuel pump flow and was good as well. Changed dist cap and rotor as well as points. Next day fired up and drove it for a few hours. The day after, I noticed it was a bit hard to start but finally fired up. Drove it 30 mins and parked. Started home and was stranded on the side of the road after backfires and stumbles like I was out of gas. Finally nursed it home as long as I stayed on the gas. Next day I checked the fuel pickup in the tank and all was well. I buy my gas at QT and have never had bad fuel but put a can of heat in and nothing. Now here is the really strange part. Fed the fuel pump from a mason jar full of new gas and she ran fine in the driveway. Today I was going to drain the tank and refill but tried the mason jar again just to be sure. Truck ran for a few then died then wouldn't restart. While trying to restart, it sucked a ton of fuel out of the jar then finally started with a huge backfire then another then died. I'm at a loss...