So, here's an update. I read the TSBs linked to about loose pins. With the battery unhooked I unplugged the EC030 47 pin connector. I looked at it, then put it back. I didn't test any of the pins, just unplugged and replugged. Reconnected the battery and started the car. The tachometer had been sitting at 7000, it immediately went down to 600 or so, normal looking idle speed. I took the car for a short drive, about 15 minutes, up to ~65 mph. I tired out sport mode and the J gate to see what would happen at high revs. The tachometer now works as it should.

Cruise still is unavailable, I'm going to have the stored codes cleared and see if it comes back.

The link for the TSB is here: http://www.jagrepair.com/images/TSB/...%20Cluster.pdf