Hi Andy,

The motor mounts were already replaced in November 2001 - and made no difference.

As I go through the chronology, if any of this starts sounding too familiar to anyone, please provide input/suggestions.

UPDATE SINCE YESTERDAY:

The car went into the shop this morning; after a test drive and speaking with tech for about 20 minutes, we're going to start with cleaning the fuel injectors. This would coincide with the general recommendations of BG 44 (I think I got that right) or the Penzoil Fuel System Cleaner.

There is a slight miss-fire every 30 to 60 seconds (noticeable when just sitting in Park or Nuetral). The tech said is was probably variances in the fuel pressure psi. He'll also try cleaning the throttle body alittle; he is very hesistant about going into the throttle body since that is an expensive part.

Also, the car has a serious mis-fire every 4 to 6 weeks when first started (last for about 10 to 30 seconds); this suggests that one or more fuel injectors is losing pressure or is blocked.

I'm hoping cleaning the fuel injectors works, but I am doubtful. This might be one of several problems, but I don't think it is "the" issue. The car always gets it gas from Chevron and a bottle of Techron every 2 to 3k miles.

When I check-in this afternoon, I'll ask about the condition of the vacum hoses. I want those replaced anyway.

ITEMS RULED OUT:

The wiring harness was ruled out because the timing issues are very subtle and there are not any of RPM spikes or stalls noted by other owners.

Flex-disc only applies to when the vehicle is moving - vibration should ne noticeable around 35 to 38 mph. Mine is smooth as silk.

WHAT'S NEXT:

If this doesn't cure the vibrations, then we'll look at the transmission mounts, motor mounts (again) and engine shocks. Before doing this, I will try the Penzoil Fuel System Cleaner; people have had good results, so another $8 is cheaper than a cup of coffee at the service shop!

GENERAL INFO ON E420 / W124 VIBRATIONS

As for the vibration itself, if the engine was in the S-Class it would not be noticeable because the additional size and mass of the vehicle would better absorb the vibration. Whereas with the V-8 in the E-Class, the chasis easily transmits/transfers any engine vibration.