Idle surging, up and down…

[Steeveedee]

I replied in General Discussion, moments ago.

Not a vacuum leak. It sounds like it may be spilling a little fuel out of the bowl when parked, and after the engine is running awhile, it clears up. I don't like blaming carburetors for anything, but in this case it may be a suspect since it runs OK the rest of the time.

To add, here- do you run it far enough that the tail pipe turns something other than dark gray? It could be that the float is just a bit too high and it runs OK except for when parked some fuel spills over.