I turned my butts at 15:15 CST they were at 178°. The temp is currently 174° and falling. My smoker temps have been ~240° the entire cook and are still there. Is this normal?
Yes. They're in a plateau. Rendering has increased and is causing temp drop. The plateau can take several hours. If you have the time you can leave it alone. If you don't, increasing your cooktemp will shorten the plateau period.