Overheats/ Peeing cold water

[Subsurface]

I have a 2006 2-stroke 90 hp. On my most-recent trip with it, it was running fine but on the way home I went full-throttle and the overheat alarm came on. The motor is peeing cold, but the stream is strong. As soon as I turn it off, the remaining water comes out very hot. I changed the thermostat, and am still having the same problem. On the earmuffs, it of course has the same problem; the water flushing out of the lower unit is warm, but from the pee hole is cold. I did have a crazy infestation of ants on the boat. I took care of that, but am wondering if there are some dead ants clogging something. It flushes fine when the hose is hooked directly to the hose adapter up at the power head and the motor off.

Thank you very much for any suggestions!

[amahaork]

I think ants just love nesting in clogged water passages of Yamaha. Cooling system completely clogged, and required to open completely and scrubbing. When I rebuild engine, some ant survive not only winter, but even trip to machine shop where cylinders were bored (I washed block myself after machine shop). and peeing stream is not indicator of clog or not water passages, only indicator that water pump is pumping water.

[99yam40]

not sure how ants can get into the cooling system to block passages while motor is all put together.

Probably just scale/salt/corrosion build up inside passages if not pieces of impeller if one came apart before.
Have you changed the water pump with a kit?
Need to make sure high RPMs are pumping enough water to remove all the heat from all that burning fuel.

as he said Tell tail is before it runs though motor