Sometimes, when I read a posted problem, I get a picture of when the same thing happened to me. I got a clear picture on this one. It's a 75 Monte Carlo back in 1987... That's the reason I keep coming back to a fouled plug. And then, I think about where I would be headed if I adjusted the carb when the problem was a fouled plug. Then it dawns on me why so many carbs are out of adjustment. I think the moral of the story came out really clear with the agreement that carbs usually don't need adjustment. Especially if you had your engine running good at some point.