I have two suggestions-
1. Use lump charcoal, it produces less ash and is thus you are less likely to have your fire choked down from lack of proper air flow. Lump also responds more quickly to intake air adjustments.
2. Cook at a higher temperature, in fact I'm beginning to think that everyone who is attempting their first butt should cook it at 275° minimum.
Warning- If that butt was raw in the middle after 8 hours in your cooker you should throw it out, eating may make you very sick.