I am having a problem with the engine rpm at idle on my 2007 CRV @ auto transmission. When warm the earratic idle varies between about 600-1500rpm. I have read in numerous searches that there are several possible reasons for this including vacuum leak, air in the cooling system, dirty throttle body, throttle position sensor malfunction or the ECM is in need of a reboot among others. I have noticed that there is no removable Idle Control Valve such as found on earlier years. Am I missing anything? The obvious places seem to be to start with flushing air (if any) from be cooling system and search for possible vacuum leak. These will be easy and if that fails where would be the next likely cause?