I would check and test any intake air temperature sensor, water / engine temperature sensor, and mass airflow sensor. (mechanics.stackexchange.com)
The air grille helps cool air reach engine better and keep engine temperature under check. (carannouncements.com)
This valve is controlled by the vehicle's computer which will adjust idle speed based upon other measurements such as engine temperature, intake air temperature and electrical system load or voltage. (yourmechanic.com)