73’ 115hp Evinrude Overheats

[Cameron1234]

Hey there,
Recently traded a smaller boat for a tri-hull boat with a 115hp 73’ Evinrude hoping to ski with it. It runs great at full speed but when moving slow it wants to over heat fairly quickly and sets off the alarm in the control box. You can see water trickling out of the ports when running with speed but much less when travelling slowly. Im wondering where to start if I should take out the thermostat first or move with the water pump, and not sure how to clean the water lines if that is possible. I was told it had a full service not too long before I acquired it.
Thank you so much for any help!
Cam

 

[F_R]

Water pump. Esp a spun impeller hub.
Has some genius already removed the thermostat ?

 

[Cameron1234]

I figured the water pump, no thermostat is still in there. What are the chances that the housing needs to be done aswell? I will take apart tomorrow when I get time but I did only order the impeller as the shipping was much faster without the housing.