Sixto - I have the exact same problem as you describe. Mine is on a '89 300TE with only 99,000 miles on it. Been this way since we bought the car at 92K miles. I've tried just about everything to get rid of this "stumble" at start up and when stopped at a stop light. If I shift into Neutral or Park, the oil pressure gage needle goes up by 0.5 bar and this stumble disappears.
Things I've changed:
cap and rotor
cleaned out idle control valve
new OVP relay
put in Lubro/Moly Engine clean - w/o results
I can't say that I don't discount that the valve stem seals are bad but it doesn't smoke at start up and it has this stumble no matter when I start the car. Even if I shut it off and start right away it stumbles for around 2-3 seconds before starting and then once started stumbles another 1-2 seconds before the oil pressure is at 3 bar.
It sounds to me like something that goes to the EZL - either it wouldn't do the same thing when in Neutral or Park.
Now, there was some reference to a screw on the back of the EHA - knowing me, I probably would have turned this screw a little. What does it do and could this be my whole problem?
My independent told me that I needed a whole new fuel distributor (to teh tune of $800) because it was leaking. That's when I started digging myself.
Any help would greatly be appreciated.
'89 300TE 99K miles
'87 190D 191K miles
'85 190D 2.2L 5-speed 228K miles
'85 190D 2.2 5-speed
'87 190D 2.5 (non-turbo)
'89 300TE station wagon