Today, with a full load in the boat, all but the trolling motor itself, and the new 8.9x6.5 prop that Mercury Marine said to use at 5000' I took the boat out and it hit 5400 RPM max and over 12 MPH max. Steady speeds against the wind and all was 10-11 MPH easily.
Problem finally solved after doing a few experiments.
The only other thing that I did was at idle it was loading up a bit so I drilled the plug they had installed over the fuel screw for idle and adjusted it. It now starts better and idles better and does not load up at extending idling.