If a bow is out of tune or if the fletchings are hitting the rest or sight window, then those arrows will NOT fly the same every time. It's no different than being in tune with a fieldpoint, only to have a broadhead looping or diving. It's all effected by the way that air moves across the arrow. If it's not coming out straight, then the flight won't be consistent. My suggestions would be to: (1)check to see if the cams are out of sync (not rolling over at the same time) (2) see if your fletchings are hitting somewhere on you rest or sight window. ( a drop away rest can solve these issues).