You have a 5 cylinder?I can totally remove 2 plug wires from mine and start it up and it will idle very nice on only 3 cylinders so don't think it's running on all 4 just because it starts or idles. I've got a vid that I posted for an entirely different reason but it demonstrates that one will idle on 3 cylinders. Listen to the sound on 3 cylinders. It's sort of like a chugging sound. It's very distinct as yours is. When all 4 are firing evenly the sound is totally different.
YouTube - Plug firing test
Seems to idle right from the get go though every time though. I guess a bad cylinder wouldn't necessarily cause bad starts. Before it wouldn't even idle or run without the choke. Checking the battery again it's at 11.6 volts again. I wonder if the battery isn't good. Think I want one of those batteries where I don't have to keep refilling with acid.
I'm probably just going to get some long fuel lines and vacuum line to do that, and just raise the tank up on something. I'm kind of cheap, lol. I don't think I'll need a long vacuum line if I just set the petcock to prime correct?There should be a vacuum port on the top front of each carb. They may currently have vacuum lines attached to them so those will have to be removed to attach the carb tune. You will need a small aux fuel tank to attach while doing the sync.