Sounds like you need to paper tune to make sure you getting good flight to start with. If you're paper tuned well, then you need to make sure your arrows are straight and that your inserts are in straight. If your inserts are crooked, then this will allow the broadheads to "steer" you arrows .
If your arrows group well with the broadheads, then you could just resight your bow for them, but I'm guessing something is out of alignment.