Hi Pete,
Yes, many of the performance mods will work with the ATV based on the same engine, so you're in luck there!
As for the sputtering, does it sound like it's the engine combustion, or is it a more mechanical feeling?
If the quad sits for weeks/months between uses, probably what is happening is there is some gas that has gelled inside the carb. This is why your fuel cleaner helped a bit, but it came back. You can run fuel cleaner again, or you can take the carb off and give it a thorough cleaning inside of it (never a bad idea to do once a year, anyway...).
Pay particular attention to getting any gunk out of the main and pilot jets inside the carb bowl at the bottom, but don't scrape them out. Use carb cleaner and compressed air to get any crud out of them.
Another issue that it might be is that your rollers may have developed some flat spots which can lead to occasional hithching of the vehicle when they pop loose. But it sounds more like the carb to me.
Let us know what you find out!
