My 40 Scout with M6 changes the idle every few return to idle. One stop will be a nice uneventful idle another will yield either widely missing idle or a dead engine sounds like ignition but a little throttle almost kills it then it runs fine and may or may not idle fine when returned to idle. I've bubble checked and tore the carb down looking for anything and rechecking the float level few times. When it idles smooth it doesn't have the dead spot just off idle. The venturi isn't quite as tight as I would like but I've seen them run looser. Takes two fingers to easily push it in and I can't feel movement when all the way in. Any suggestions? This carb has been issue free for the last 10 years. Cotten?
Dusty