Bike Idles weird

hey whats up new 2 the sight just bought a 05 sv650s been wanting one for a while now,a couple of days after purchasing it started to idle real funky it surges from 1350rpms to 1000rpms,could anyone help me out with this,im starting to get a bad attitude,i cant figure it out cleaned air filter, checked plugs ,adjusted the idle nothing helps is it possible its just bad gas......thanks