Update: Took me 3 months and 9 cooks to figure out my heat problem was the lid seal
I kept getting hot spots on my offset and chased everything else for way too long. Replaced the thermometer, tried different wood, messed with my intake settings, even changed how I stacked the coals, and none of it helped. Then a guy at a contest in Waco asked if I had checked the seal around the lid and I just stared at him. The gap was maybe 1/8 inch but it was pulling air the entire length of the cook chamber. Ten bucks of gasket tape from the hardware store fixed in 20 minutes what three months of guessing could not. Anyone else waste a whole season on something dumb like this?
The crazy part is that tiny gap does way more damage than people realize. Air sneaks in cold right along that whole seam and it messes with your draw, so the fire rushes on one side and stalls on the other. I had the same thing but on my firebox door, maybe a 1/16 inch gap at the bottom, and it made my temps swing 50 degrees. Once you seal it up the whole cooker just calms down and you finally trust your vents again. Check the door too while you're at it, because a lot of guys seal the lid and forget the intake side is leaking just as bad.