Originally Posted by oldbill
After reading all the posts, the only thing that I see that hasn't been addressed yet is airflow. If you're building the fire too big and having to choke down on the intake damper too much you will get dirty smoke. Try keeping your exhaust damper wide open and then controlling the heat with only the intake damper. If your intake damper is 1/3 to 1/2 open and the temperature is getting too high, your fire is too big.
I have to agree with oldbill's posts.