Check ground wire that is bolted to chasis just in front of chaincase. Also check to make sure all coils are tight and no wires pinched. From you are describing I would say it is an electrical issue. I also di-electric grease all my electrical connections just to make sure no moisture gets in them. Ive had all brands od sleds give all sorts of weird symptoms when get moisture in a connection.
Found a problem on a 2015 8000 belonging to my son. Look down underneath your y pipe and find the throttle body/oil pump linkage. Move the throttle flipper while looking down there. A small light and mirror or an inspection cam helps. Found on his that oil pump was getting hung up, not returning with throttle. I was staying half way open in a nice warm shop. Only way it would close was to open throttle wide open and let it snap back into place. That little flimsy watch spring is not woumd tight enough to do anything. We put a tiny o ring over the two pegs and a dab of high temp silicone to keep it in place. Now the oil pump closes back to its idle position every time. No more garbles, gurgles, bogs, choking plumes of smoke in sled trailer. Condition worsens if you are out in the cold lots. Oil bog.
Almost guarantee this is your issue. If that little return spring gets dirty at all it will not pull the linkage back at idle (not even close). You will be loading that engine up with oil anytime you are not really getting into the throttle; such as crawling along a tight trail thru the trees... etc. I just check it and give the spring and linkage a spray of Power Lube to keep it clean and freed up after every trip.