on the rough running, here we have (2) selections for "regular", 87 octane and 89 octane "gasahol" that is 10% ethanol & 90% gasoline. Every year as the weather heats up some carb based cars that are on gasahol start to run rough(or die while idling) & some dont.The ones that do have a problem if they switch to 87 octane that cures it. Interesting thread & I am real anxious to hear what the problem(& the solution) ends up being for you.