I have not had an R107 in quite some time but do remember an issue with the CEL when the odometer reaches a certain mileage indicating that the O2 Sensor should be changed out. If memory serves there is no way to reset the CEL and most owners remove the bulb from the CEL. Additionally, if the hard start after sitting is while the vehicle is still warm you may find the issue is with the Fuel Accumulator which is a simple fix. If as Frank mentioned above the hard start is from cold I would follow Franks' recommendation for testing.

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82 380SL 41K miles sold, 98 SL500 44K miles, 13 C300 4Matic, 14 CLA-250 4Matic