Hi there from freezing cold Fredericton New Brunswick Canada.
My wife has a 1999 c280 sport w 107.000 kms that has started to give her some trouble.
We have owned the car for 3 years and have had an extended warranty for that time.
We have done the crankshaft balancer, mass air flow, electronic climate control under Warranty.
The problem now is that upon starting the car it will start and then the R.P.M.s will fall and almost stall or stall the car at start-up, it will recover and idle fine.???
We have not changed the plugs, wires or battery
Any thoughts why this might be occuring.

Thanks
Lance.

Do you mean the crankshaft position sensor?
Similar symptoms with my C280 fixed with new spark plugs.
Dan

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2012 E350 Bluetech

Hi there forp, good point about the crank position sensor
but the crank shaft balancer was/is a specific recall on the v6 engine.
I am planning on doing plugs, wires, etc, very soon, I was just wondering if it might be something else i.e. mass air flow sensor again or Ignition coils, relays????

The crank position sensors do wear out and can leave you stranded on the side of the road. If yours is the original, it is probably on its last legs. If you plan on driving this car for a while you should replace it. It is a very easy DIY. I think you can find them for around $80 (American).
I just replaced my spark plugs at about 67,000 miles. Your car's mileage is about the same. After removing them I could see that they were noticeably worn. IMHO, the recommended 100,000 mile interval is too much. There is also the issue of damaging the threads in the aluminum head if the plugs are left in for too long. The spark plugs have been in your car about 7 years so it would be prudent to replace them even if they are not causing the problems you described. If you decide to replace the spark plugs yourself, do lots of reading in this forum for cautions and tips (EX: Don't listen to anyone that tells you it is OK to use resistor plugs in this car. OEM plugs are non-resistor, replace with like).
Good Luck, Dan

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2012 E350 Bluetech