Have a 2004 35 Fountain with 525's port motor is running way hot 195. Changed sea pump impeller and back flushed still running hot. Any thoughts on where to look next?

I had an issue once where a tiny rock made it's way to the thermostat and stuck it. Worth a look maybe.

I had similar issue with a 502EFI closed cooling system. Took the end caps off the heat exchanger and found some gunk, cleared out the passages with a thin metal rod. All was good after that.

Go thru your heat exchanger and sea strainers.