Your engine is the same basic engine that is in my car (see my signature below) and all other M104 2.8 and 3.2 liter engines in E320's, S320's, and C280's until 1997 (or 1999 for the S320).
I would also guess that your problem might be the throttle actuator, otherwise known as the EA / CC / ISC module (Electronic Accelerator, Cruise Control, Idle Speed Control).
I don't believe your car has a cold start injector, but I could be wrong.
The problem could also be the mass air meter.
The mass air meter isn't too expensive at around $250-ish. It is very easy for a DIY'er to replace. Takes a screwdriver and 10 minutes to replace.
The throttle actuator is about $1,200.
Either part is too expensive to take a stab in the dark, so I'd recommend taking it to a shop so that they can diagnose it for you.
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".