Lately my car has been revving itself up and down when I 1st turn it on. on 2005 Mercedes-Benz C230

The RPM goes up and down roughly between 30-40 rpms until I start driving it This happens in the morning and goes away as soon as I begin to drive...Does something need to be replaced?

Asked by for the 2005 Mercedes-Benz C230
is the check engine light on , did you pull the air cleaner off ? sounds like a vacuum leak ,i could be wrong ,