Q: Car is overheating - 1999 Pontiac Grand Am

Alright, When I first bought the car the guy i bought it from told me there was 2 problems with the car. A camshaft sensor and a map sensor. I replaced both of them, and the car still didnt crank. I think I may have flooded the engine so i let it sit overnight. Went out the next morning and it crank right up. So I tried driving it down the road and it died every time i tried to give it a little to much gas. So i unplugged the mass airflow sensor now it runs perfectly. I drove for about ten minutes and noticed my temperature gauge started rising. I parked, looked at my reservoir tank and there is a hose that's completely cut off from everything else, I looked it up and it said it was a pressure relief hose, it releases all my coolant and water if there is too much pressure. So its supposed to be there so now im confused. Could this be a water pump problem? I bled the screw that makes water come out so I know there isn't a problem with my thermostat. Is this a water pump?

My car has 183000 miles.
My car has an automatic transmission.