Hi hello!

this is my first post... i have a question on a rough idle in my 1998 C280... i have searched the entire forum, and found some similar posts but not exactly the same...

anyway, my engine runs rough as if the idle was too low (idle points to around 600-700) when the car is at a stand still and in gear. however, if i shift the car to park, neutral, or reverse, the engine idles normally. otherwise, whenver i am in "D" and at a stop, the car idles rough and will disappear as soon as i step on the gas, at which point the car's drivability is normal. i haven't seen any temperature-related patterns, although it always happens during the first 15 minutes of driving, and only sometimes happens after that.

can someone plz provide me with a methodical solution to pinpointing this problem? thank you!!!!

car specifics: 1998 C280, about 55k miles, always scheduled maintenance items performed per schedule by dealer