91 75hp Merc weak stream???

I haven't been using my boat that much but while I was using it today I noticed that my water stream from the side of the motor was weak. It doesn't seem to have very much pressure. It made a little spitting sound when started out the water hole like it was stopped up or sucking air for a moment. I'm really not sure. Anyway I ran it up to 3 miles back to the dock and the stream was still weak but running. I put my hand in the water stream to see if it was hot and actually it was on the cool side. It was warmer than the lake water but still fairly cool. Maybe it needs flushed out or something, it had an impeller put in last year. Advice?

1. Does this 91 elpto Mercury have a thermostat?
2. Does it sound like a bad impeller or stopped up?
3. How can you tell if a motor does get hot, do they have an alarm?

I'm sure I'll probably take it to a mercury dealer to check it out but would appreciate any advice. Thanks.

it should have an alarm,and the p stream would be hotter than normal too.
did you watch to see if it was a harder stream as you revved the motor?i would doubt you have a bad pump that soon it may just have an obstruction in the p tube.do you have a pressure gauge?if not i would install one that way you know,my johnson stopped all the way up in the fitting on the motor with a piece of leaf but the gauge showed 30 psi while i was running.

The stream is a little stronger with higher rpm but still weak. As luck would have it my pressure guage isn't funtioning. At the end of last year it was really putting out a good stream. May have to clean it out and put an impeller in just to be safe. But at least the stream is not hot. The motor never seemed hot from the outside and ran perfect. I wouldn't have noticed it until I heard it making that spitting sound as it started.