I bought 2 pork butts at Sam's Club. Every other time I have bought there, they have turned out great. This time the roasts were a lot more dry and tough than normal, and had to be cut - they would not pull apart. I cooked them for multiple hours at 225 degrees. At 160, I pulled them out and foiled them, and took them out at 197 to let them rest for 25 or so minutes. What did I do wrong? Or is it possible that some pork butts just have not near as much fat and don't turn out good?