Mitsubishi Repair: engine overheats, radiator core, coolant level

Question
I have a 2001 Diamante.  The engine has begun to overheat and when this happens the heat in the cabin gets colder.  The coolant level seems ok and the engine oil level, while it may need changed, is ok...any ideas

Answer
Jason: Got some ideas to check, because it could be one of these or more... water pump faulty, radiator core blocked or grille restricted, thermostat faulty, electric collant fan blades broken or cracked, radiator cap not maintaining proper pressure or ignition timing incorrect. I tell people to get a repair manual for their cars, you can get one at any parts store for around $20.00 and well worth the money. It will explain how to check these things. The fact that the air in the cabin gets colder says to me either the water pump or that thermostat is bad. Hope this helps and good luck!