13 800s jerky under acceleration

Hello, first of all the machine is stock aside from cosmetics.

It has been on and off jerky when the belt finally grabs to take off. It seems worse in cold weather. It also doesn’t seem to top out much past 40mph which I think is kind of weak. I added a snorkel kit to it and since then, the only riding I have done is a 14 lap brolite truck course with two jumps. After it was over I drove it around and it was normal. Then it sat for a few weeks. Once I started it and was doing some light driving around I took it out to do some tree stands. And it is just grabby and studdery. Once im in the throttle and at some constant speed it is fine. But I started at one end of a hay field and floored it for about 300 yards, the fastest it got up to was 40. Seems very sluggish for this sort of machine, but I have no other one to compare it too.

When I did the snorkel kit, I removed the clutch and sealed the back of the cover and everything looked like it was in good order. Belt wasn’t burned or worn. machine has 220 miles on it. And its never been "fast."

I don’t know alot about the machines either so Im probably contemplating taking it to a dealer next to see if they can sort it out if nothing comes up here.

Thanks in advance.