Ive got a 73’ 350 scrambler that runs like a champ until it gets 40-50 miles on the trip odometer. At that point I’ll experience surging and sputtering- switching the petcock to reserve provides no relief. Tank has little to no rust and the fuel lines have filters installed after the carbs were rebuilt. Stopping at the gas station and filling up again and she runs like a champ again. Clogged petcock? The next phase of the mechanical restore The plan was to reseal the tank and rebuild the petcock Might need to move that up if that is the case. What do you think?