Thanks for the reply. During my first cook, temps were llniver the place. I've been doing a lot of online reading today when I was "working" and think I've deduced a few things that I was doing wrong. First, I know there is a leak at my firebox door (the one in the side). I know that I'll need to solve for that long term, but it likely isn't in the cards right now. Second, I started off using only one chimney of charcoal. I've seen some of the expanded steel baskets and it looks like I totally under-fuelled my fire from the very beginning. I'll fix that for my next cook. Third, as coals burned down and I added new coals, I never cleaned out ashes. Essentially, I started suffocating my fire from the moment I put it in the firebox. I'll try to remember not to do that again. Fourth, I think I was losing a lot of heat directly out the stove pipe. I've already added an extension to grate level. Hopefully that will help.
I hope I'm not too excited before my next cook and I remember to correct the sins of my past.
I do have an additional question though. Would using wood chunks instead of split logs contribute to the wildly fluctuating temps?