1999 Acura CL • 4 cylinder FWD Manual • 158,000 miles

I have a 1999 Acura CL that is overheating when in idle. When driving the temp gauge drops back down to normal. I had the termostat replaced and the Cooling temp sensor replaced and it's still doing the same thing while in idle. Does anyone know what could possibly cause this? It's full of engine coolant and does not appear to have a leak anywhere. Both of my fans are coming on properly it appears.
December 9, 2010.

Have you checked for air trapped in cooling system?
Are the cooling fans turning in the correct direction?
Does turning on the heater reduces the overheating?
Have you checked the radiator for clogging?

Dec 10, 2010.