Michele, at 166 if you are doing pulled pork you still have a long ways to go, 195-200 is the temp you want when you go to pull. How heavy of a butt did you use? Also was it bone in or boneless? At 180 you can back down on the smoker if you think they will be done to early. Also I great trick is to wrap the butts in foil and place them in a cooler wrapped in a towel. This will keep the butts hot for up to 4 hrs. It also gives the meat a chance to rest. I always put my butts in the cooler for at least two hrs.