Here is the history of work trying to remedy.. open to all suggestions...
Ebay buy in 2013, with only 61K, now has around 80K.
Ran a little rough (very intermittent) when I got it at low speeds but seemed fine on highways. Drove it between Stuart FL, and Charlotte a few times and after some 15Kmi the frequency of the rough running became very regular. I replaced caps/rotors in this timeframe.
First indy diag seemed to think it was the MAS as a shot of cleaner seemed to bring her back to life..
So, I decided if it was the MAS lets fix her.
First repair was MAS, crank sensor and fuel filter, and new ignition module. No difference.
Did smoke test, no leaks reported.
Tried a 2nd indy, and we suspected the throttle actuator, so sent to beckman who confirmed it was good. Tried another crank sensor, No improvement...
Ok so now it seems indy friends are stumped, so since RennTech is in my backyard, I figured they should have some experience with the W124 so I explained the history, what had been done and gave it to them. They quickly turned it around after 9 hours of diagnostics as fixed by swapping two vacuum lines... took it home, drove for a week, (went away for 2) and when I came back, drove it all of 2 miles and rough running returned and would quit. ($900 bill!)
The car had been left with Renntech for 6 months and they claim they could not duplicate the rough running, so in dec I returned to pick it up. Drove it around the block and rough running shows its face again.. so drove it right back to Renntech.. Their lead technician saw it running rough in their lot so i left it with them.. again. Its now march and I got an email saying they cant duplicate so car should be picked up.
Will be getting it in the morning 3/2/2017.
So, I hate to abandon such a beautiful sedan...
Ideally I might find a well running example and use it as a reference (and perhaps part swapping), but need to find a <new> friend in the Stuart, FL area.. OR.. start throwing parts at it.. OR even considered taking it to West Palm MB since they have been around for a while and may have older tech familiar with the model..
I have begun considering buying another (working) E420 to help get this one back on the road.. just not ready to make that decision just yet..
any questions/suggestions? I will be rewarding those who are key to resolving this issue (non monetary rewards )
thanks in advance