This has finally taken a turn for the worse, so I'm going to try and tear into it this weekend. I was able to Fonzy it along for a while, but that finally stopped working. I had a CEL show up the other day when the cluster finally completely "died". I pulled the code and it's P1698, which is indicative of a possible ECM issue. Further research shows that the cluster having problems can interfere with the CCDBus, causing communication issues between the ECM and TCM.

Anyway, like I said I hope to tear into it this weekend and fix it up. It still comes back here and there.