hey guys (and gals) i have a 1999 ZL 600 EFI with 3000 miles on it that i just bought and it was full of Sta-bil and didn't have any top end so i put new plugs in and pumped the crappy gas out and put in 91 octane and it still has good low end but cuts out around 6-7 grand it gets worse n worse and sometimes it's fine there is no reason that it does it, it's random. spark? fuel? any help would be greatly appreciated!!