My first suggestion is to cleac the throttle plate with, of course "Throttle Plate Cleaner",
My second is to: Lube the accelerator cable, dirt and rust can make the cable "stick".
My third is to: Check the coolant temp sensor, mine was unplugged and my car idled at 1200 rpm, I peeked under the hood and I saw the sensor was unplugged.
Hope this helps
1987 mercedes 300E
1995 e320 conversion(hated the 300e grill)
Monochromatic Paint (Custom Blue)
Flat Badged (front)
custom "carbon fiber" console
18 inch HP EVO rims
Sold! Now I drive a Monte Carlo SS