Thank you for posting this advice. I really appreciate it.
Thanks to all the feedback that I received I was able to pinpoint the exact reasons for my runaway temperatures. I was using far too many coals and I had a tremendous air leak from around the lid. I have since cut back on the number of hot coals that I start with to just 22. This seems to be about perfect to get my drum to 225. I have also installed a gasket around the lid to seal it.
Also for my air intake I am now running two 1 inch ball valves. I discovered that one just wasn't enough airflow to bring my UDS up to the desired temperature.
Chargriller Pro w/o smoke box.