Thanks for tips. I did check everything and it was all fine. I had seen a 3 or 4 degree drop, but not ten. It was already out of 140 degrees. It got to 150, plateaued, then dropped to 140 slowly over a few hours. Then came right back up and pulled it at 165. Seemed very weird. My fire was at 215, I brought it up to 235 about halfway through the plateau. Very, very big drop if you ask me, but it ended up fine.
I did steam my pastrami at the end. Very good, but I wonder how to make it even more tender. I left the temp prob in it and when it got to 205 I pulled it off the steamer. Took less than an hour. Wonder if leaving it on longer would have been better.