1994 Pontiac Grand Am cooling system

Could be the water pump but for your sake I hope not sometime the propeller can come loose on the shaft therefor preventing it form doing it job effectively

to answer your question about the whereabouts of the thermostat it's located where the lower rad hose connects to the engine(back below the manifold)
and the water pump is located behind the timing chain which mean the timing chain has to be removed to change it

seeing as it's a quad 4 if you need the pump changed take it to someone qualified to do the job the timing in these motors can be tricky