Thanks for the feedback, man.
My pecan chunk was about 3/4 fist size, but I'm not so sure that the larger size was the issue. I've used chunks that large before with lownslow cooks and didn't have rolling dense smoke. The charcoal was really stoked, though. That's what was different about this cook. Just trying to get crisp chicken skin, AND I DID.
If you're lookin' you ain't cookin', but if you're overcookin' you might start lookin'!