I didn't do anything to the gasoline that was in the tank. No idea what percent ethanol it was, either, though I've cycled through a few tanks of gas since. Back when all this was happening I adjusted the valves. They were all almost perfect and very few needed any adjustment.
I'm wondering if the leather piston in the carburetor might have dried up while the car was sitting and maybe now has some kind of problem where it doesn't always function correctly. The problem is really intermittent. It will do it about once every day and that's it. Temperature doesn't make a difference. It does it hot and cold. It does it in all gears. And it happens only when I step on the gas. Just a short cough out the carb. The carb is a Rochester model B that I rebuilt about ten years ago and have never had any trouble with. But I do recall that the throttle shaft seemed a little loose in the body of the carb and I've read that this can cause the problem I'm having. I stated in an earlier post that I did the Marvel Mystery Oil upper end cleaning last year.
