I recently got this impeccable 1994 E320 Cabriolet, 2 owners and all records, 101K miles, CA owned all its life.
30K in receipt over that last 5 years, includes new head, and harnesses, hoses belts, new top, and associated hydraulics.
driven 3K miles over the last 6 years.
The second day I drove her , she drove great, good idle and power.
But I turned into my parking space, and the idle became very rough..
Drove her a little more, power is really nice, but idle was horrible.
I am a good mechanics on Mercedes, but this is a strange problem.
No vacuum leaks, tried another MAF, no change.
No check engine light either, coils and plugs are fine.
Could I have a VVT issue ?
Thanks.
Henri.

 

Check the cap & rotor. Frequently when my 400e ran rough I found moisture inside the distributor.

You said harness was done but double check anyway. Same with throttle controller.

 

Clean your idle control valve. It's likely stuck from sitting. Also, check the throttle body electrical connector; it can come loose when turning.

 

direct ignition, no cap or rotor . Harness is like new , throttle is a cable . Checked cam timing , indeed vvt was set to full advance , manually set it back to full retard.
Think the 320 never saw rpm over 4000 .
vvt actuator stuck .
She runs good now , no issues