It seems like things are more finicky when you have lit and unlit coals - temps go down as the top-coals burn down, but go back up as the bottom coals come on-line. It hasn't hurt anything yet, so I'll get used to it, but if there's a better way to narrow the range I'd appreciate the tips. I need to mark the positions of the bottom vent, and my intention was to manage mainly using the top vent but that wasn't possible as at one point things dipped well under 200F and I needed to get some air in there. Toward the end of the cook, things got a lot more stable. Not sure if that was a sweet spot on the vents or the coals got themselves to an even state (or both).