2002 Infiniti Q45 • 177,048 miles

Hello I have a 2002 infinti q45. Its just started overheating only after I start driving. If I let it crank and just sit cranked up it wont overheat its stay cool. I installed new thermostat, radiator not leaking, fan coming on, thers no sign of water and oil mixing or water shooting out tail pipe. Someone told me about the coolant temperatue sensor, but I havent check dat problem. Do you have any advice on what could be the problem?
July 21, 2012.

Check the coolant level, water pump circulating coolant, collasped radiator hose/s and also try bleeding the cooling system and see what happens-let me know

Jul 21, 2012.