I'm assuming that it is running rich?

Not sure if it is the same problem but I spent weeks trying to find a similar issue with my 82 380SL that turned out to be cracks in the air chamber which could not be seen and my duty cycle was at 90%. I only found it after doing a smoke test. The cracks were allowing additional air into the system which told the system to add more fuel. Unfortunately, I had replaced many unnecessary parts in the process. if you think there is a chance it is the same issue there are posts on this site with photos.

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