This did the trick. I must have gotten a bad tank. I think advancing the timing to the scribe mark helped with power overall, but changing the fuel filter definitely fixed the problem with power at higher RPM. I feel like an idiot for not checking this sooner.

I will check my receipts and find out which station it was. I think I know. A buddy who is a diesel mechanic says Charlotte is really bad about bad diesel. He says to go just outside of Charlotte and you are a lot better off. Of course, living on the border of NC and SC helps because fuel in SC is at least 30 cents cheaper.