Hi. I just got a Char-broil electric smoker and used it the first time to smoke a shoulder roast and a small ham from a wild pig (about 5 pounds total) We cover the meats with a dry rub and smoked them at about 220 degrees for about 4 hours or until the internal temp reached 180 degrees using Hickory chunks. The taste was great but meat was tough and got tougher as it cooled. Do I need to cook slower using lower temps? Any suggestions would be appreciated.