Some snowmobile carbs have a high low adjustment on them. The banshee carbs do not. The airscrews only adjust the pilot ckt. As daj brought up, if it is colder out then last time it was running well, you may need to richen it up and would exlain that problem. But if not, you need to look at anything that would restrict fuel flow. Once you have eliminated all that, it is time to start thinking electrical.