I have had my 2004 coupe with auto trans for 3 years now. I continue to have an issue with low idle. When I first start the car it idles at 700rpm. After it warms up, it drops to 500 rpm and feels like it will stall at stop lights. It never does stall. Is this normal? I have had my mechanic check for vacuum leaks and none found. I have also done the following over the past 3 summers:

New : spark plugs, fuel filter, air filter, crankshaft position sensor, MAF cleaned, throttle body cleaned, no engine codes, new battery.

Any suggestions or is this idle normal?

Thanks