I bought one of these a few weeks ago, did a couple dry runs to get the shine off the inside & smoked a bunch of chicken in it last weekend. Tonight, I'm trying to smoke a brisket and pork shoulder & lit the fire using the Soo Donut but cannot get the temperature below 290. I'm using Kingsford Blue and a few oak chunks for smoke and have a full water pan. All vents top and bottom are now 2/3 closed, but the temp is staying up. Any advice on getting the temps down would be great.