I have a 94 E420 too and it loves a one hour plus, consistant high
speed drive on the highway, from time to time. Car starts, runs, idles
smoother. These cars need to be driven. I guess the consistant;
vibration, heat, vacuum, oil and fuel pressures align all of the E420's
complex operating systems. Short drives create inconsistantency between
I 'm not sure if this will help you with your problem but it may be
worth a try...