I bought my dads old sled recently that was sitting for 5 years. I had my uncle go through and clean the carbs since he’s been doing it for years. put new plugs it and got it to run. It was idling around 1000 so I adjusted that and got it around the factory setting of 1500. When it first starts and warms up it’s good but when I run it for a while and come to a complete stop and let of the gas it goes back down to 1000 and dies. I’ll start it again and it’ll idle between 1000 and 1500. Why does it die after running it? Any help would be appreciated.