Fast Idle Speed
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 1997 Mercedes-Benz SL500, 1997 Mercedes-Benz SL320, 1997 Mercedes-Benz E420, 1997 Mercedes-Benz E320, and 1997 Mercedes-Benz E300. However, it is still accessible from the selected car via links, so may be relevant.
Fast idle speed is controlled by electronic control module for gasoline engines, Idle Speed Control (ISC) module on E300 Diesel.