Help with my problem: I recently prchased a 97e420 from Westmont, Il with 43k. the car ran fine the first couple of weeks, then I noticed that when coming to a stop the rpm gauge would start to fluctuate along with the engine. The next problem was the engine seemed to be missing. It doesn't matter if the engine is cold or hot, in gear or in park, a.c. on or off. If you power brake the car in drive gear you can feel the engine miss a lot more between the rpm range of 700-3000. It seems worse when its in between 1500-2800. I did the 45k service with all factory parts. My friend who is a MB tech. hooked the car up to a factory scan tool, watch the car for 3hrs. and could not find anything wrong with the computer sys. The computer only had a code for the door locks. We checked the wiring harness and still did not find anything, also when driving at cruise speeds in town, you can feel the car missing up to speeds of 45 mph. and then it seems to run fine. The car seems to get 25mpg. on the highway and 12 in town. Any ideas?

If it's missing and also lacking power, I would suspect the mass air flow sensor. I've also seen the O2 sensors cause problems like this, but you'll normally have trouble codes with these. Usually with a bad mass airflow sensor you'll have codes as well, but with this system, you may not.
Did this problem occur right after doing the 45,000 service, or did it take awhile? Or was it doing pretty much the same thing before the service? Were the plugs replaced during the service, and if so were they the proper (Bosch F8DC4) plugs?

Gilly

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