It's only a 4 cyl. I live in the land of big hills, so it often needs to kick out of OD to keep the speed up. It doesn't do this until it has started an accordian effect with the cars behind me. Usually I'll end up hit the OD button myself.
I don't think anything is broken, it's just the way it is setup. On my 87 Camry it could be adjusted electrically, as per last post. I only have a Haynes and it doesn't say squat about the CC and the WD is useless.