It sounds like it's getting hot and triggering the temp switch.
Check the inlet port for the cooling water on your model.
Based on the part diagram at
94 MONTE CARLO
under water filter tab, your inlet is the same as my 95 Montego DLX. It's in the rear of the hull (outside the hull ) in the top of the chunk of aluminum right before the steering nozzle. There is a 90° hose coming off of it and going into the hull.
I'd check to see if it is clear in the aluminum and in the hose.
It also looks like your model has some kind of filter. You might check it as well.