2000 Prostar 205V Overheating

[NewbieMastecraft]

New to me 2000 Prostar 205V. We've only had it out 4 times. 125 Hours on the engine - the standard Inmar 310HP EFI. Several times the engine has overheated, going into the "limited RPM" mode, usually just idling out of the No Wake zone. Every time except yesterday it has cooled down to normal after a few minutes at 12-1500 RPM. Yesterday it did not cool down and we had to return to the dock.

I've seen the posts, and everyone I've asked says I probably need to change the impeller, but I have another question.

The first thing I did when we got back was to put the boat on the lift and check the cooling water intake under the boat. Behind the brass cage, there appears to be a piece of something that I can best describe as looking like a Scotchbrite scrub pad. It appears to be cut and positioned like its supposed to be there, but everyone I've asked (including Mastercraft) says "I don't think that's supposed to be there - unless someone installed it as some kind of filter". However no one says "Take it out of there".

Has anyone ever seen/heard of anything like this covering the coolilng water intake hole behind the brass cage? Is the hole supposed to be a completely unobstructed clear hole to the water intake hose? Should I just take it out and see if it cures my problem? Any help or comments are appreciated.

Also, if I do need a new impeller, does anyone know what part number I should look for? Thanks in advance.