Renault Megane

If it is the IAC valve, you can try it accelerating and releasing, if it falls to less than 1000rpm and then it is paired it is the dirty valve.

The step by step I do not think it is since if it were this, the scanner detects it to you, it also had to pass you throughout the day. You can disconnect the same that nothing happens.
Good luck and greetings ..

If, apart from the game in the mornings, the resistance of the temperature sensor, the IAC valve if it regulates badly does it throughout the day, not only in the mornings of any way clean the admission body.