Jack M, the Oxygen sensor warning light will illuminate under certain circumstances. I am passing along my experience with our 1991 300CE that had no Oxygen sensor warning light; however, replacing the Oxygen sensor resolved the acceleration hesitation. A local indie suggested that a new Oxygen sensor "may resolve the problem", but he didn't want to charge me for a replacement and not be successful resolving the problem. Since I am a DIY'er I replaced the Oxygen sensor myself. Not difficult, but you need the crow's foot tool with the slot for the sensor wire. Obviously, the best situation for you would be to temporarily install a known good Oxygen sensor and see if that resolves your problem.

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Fred Hoelzle