2009 Evenrude 200 HP is revving up while running

[lts365]

My Evenrude motor is making a noise like it is not getting water pressure, even though it is getting 25PSI, while running, it only does it when I have a fully loaded boat and mainly in rough water. If I continue running it the alarm will go off. If I stop the boat and turn off the motor it will reset for a little while.
I have had a Evinrude certified mechanic who said it was the prop and replaced the prop and that did not work. Also just had the water pump replaced.

[boats.net]

Need to check engine temp with infrared thermometer when buzzer goes off to see if engine is running hot.