Another goofy way to tune them together is to strip the fletching and shoot them bare shaft. Rotate the nocks until they all hit in the same place. Any that won't go in the same spot, replace the nock and try again. If they won't group use them for stump shooting. You will get two or three bad ones per dozen usually.
Once you get them all grouping as bare shafts, then fletch them up the same. Test again and refletch those that aren't grouping.
This is a very common technique for olympic recurve archers where the ACE or X10 arrows cost between $250 and $350 per dozen.
I didn't see which broad head you were using, but if it's Muzzy's that part of the problem right there. Muzzy is a great broad head, but has the weight way further forward than a field point. This can send your arrow out of spine tolerance very easily. Go up a spine weight if this is the case and you should be able to get them all to fly together.
Cheers,
Pete