Car does NOT overheat when idling. Idled it for 20 minutes in the driveway and the temp gauge stayed right in the middle. Drive it for 5 minutes and the temp starts to climb to a place where I'm not comfortable keeping the car running. Brand new fan & clutch. Water Pump & Thermostat changed about 7k miles ago during timing belt service. Aux fan only comes on after I shut the car off and runs for 15 minutes on & off until the car cools.

I'm replacing the Coolant Temp Sensor & Aux Fan Switch today, but I have a feeling I'll still be having this problem.

Any ideas what this could be?

Help, before I drive this damn thing off of a pier.

 

Make sure that the coolant system has been bled of any air. If there is air in the system it will run hotter than it should.