For the last two weeks, my 2003 CR-V LX has been experiencing idle issues. It starts and idles fine initially, but after driving for 40 minutes to an hour, when I park, and let the engine idle, the rpm starts to go up to 1500 rpm. The longer I let it idle, the higher the RPM creeps up. The temperature is normal, and the cooling fans operate as it should. Just to be thorough, I replaced the IAC valve along with a new gasket, but the problem persists after driving for over 40 minutes. I also checked for possible coolant air pockets in the radiator, but there were none. What else could be causing the idle to increase?