Hi Andrew! You've come to right place, I'm sure someone here at TMW will be able to assist. Some background information will be helpful in diagnosing your issue.
First, what's the history of the bike? Have you owned it for awhile and this started out of nowhere? Or did you just buy it from someone and discovered the problem?
Second, does it have any aftermarket parts? Sport exhaust, power commander, like that? If it does, were they just recently installed? And were they installed by a professional or more DIY?