So I have a bog that just doesn’t go away. I took my sled out to the mountains for the first trip this year and it ran good at the start of the day, but as the day went by it kept losing power and almost felt like it was hitting on one cylinder. It did this for 4 days. Runs good at the start and runs terrible come the end of the day. I changed the plugs and fuel filter but didn’t work. Pulled the plugs and they were fouled. While I’m riding I’m constantly leaving a black trail in the snow from exhaust. Here is a video of it from the end of the day.