Hunting at 3500 rpm

[nickodemon]

Bought myself a standard fazer 1000 gen 1 and it is really good. I've been using it for a few days now and the only slight issue is it seems to be hunting slightly on a steady throttle at 3500 rpm. It's so long ago when i last rode a standard fazer i can't remember if this was a common problem or if there is a solution. The only thing i could think of was old fuel as the bike had covered less than 300 miles in 3 years? I have fitted a venom race can with the front db killer in and the rear one out.  Ps.. It seems to be slightly worse when it's cold.