Everytime I try and to smoke a Boston Butt it always turnes out tough and reaches temp. way too fast. It takes me a little over 2 hours to smoke a 5-6 lb. roast. I smoke it at 225f. I'm using a char-broiler with a firebox burning lump coal with hickory chunks. I take the internal temp. to about 200f then let it settle for about an 1/2 hour. Any idea would be great.