I was delayed by weather and life in general but I finally got the plugs changed and took if for a test drive that included going up the same hills where it was acting up. That was running about 55mph in 3rd gear at max boost. Everything seems to be good.
I have watched the dash gage for transmission temperature before and never saw it increase from normal operating temperature. I suspect that may not be accurate but never got around to figuring out a better way to monitor it. I hope to work in dropping the transmission pan soon and replace the filter. If everything looks good I will stop with just cleaning it up and replacing that portion of the fluid.
Thanks for the help!