The 460 I've got is not wanting to come back down to idle when revved or cutting and you let off. It ran fine one day put it up and the next time I tried to run it this started. I've adjusted the carb everyway I can think of. It isn't ported just a dual port muffler. The high limiter is gone, and the low is still there. It runs just fine and the plug still has good color. It will start when warm and idle fine without using the high idle. I pulled the carb off and checked the boot and couldn't find anything wrong with it. It doesn't matter which way the saw is either, on each side or straight up or down it still does it. I don't have stuff to pressure and vac test so that is out for right now. I'm boxing up tools to move by the end of next week so I won't mess with it much unless someone has some simple things to try.