I had what I would call MAJOR hesitation problems on my 1991 300SE. This was AFTER new injectors, cap and rotor, plugs, plug wires, lots of injector cleaner and carbon cleaner, new fuel filter etc.

Always, once the car was warm, there was a HUGE hesitation (all most a stall) on startup. My trusted MBZ mechanic thought it was a combination of carbon build up & a weak fuel distributor. DID NOT want to replace the fuel distributor at $1000 plus. This is for a Bosch rebuild (do NOT buy a $300 rebuild).

I saw an idle control valve ICV on Ebay brand new for only $120 inc shipping.
So I took a chance. Immediately upon installation, which was easy, there was a HUGE improvement. Probably a 90% improvement. So this is my story. I would first try injector cleaner and carbon cleaner, available at all import auto stores. Make sure your spark plugs are good and the right OEM type, before you spend any big money. The ICV is around $200 plus. Good luck, I do not know if my car was a fluke, but I am glad I did not have to buy a fuel distributor.

PS my 300SE had 140,000 miles, never apart

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1994 E320 Cabriolet
1992 300CE (Sold)
1991 300SE (Sold)
1986 560SEL (Sold)