Congratulations! Sounds like my 88 when I got it. Only 2k miles in the 10 years before me! I even have the same white and grey!

After the tank got flushed, a few fuel lines replaced, some Sea Foam and a can of BG BK 44 it got better. I also replaced the plugs, plug wires, fuses, and distributor cap.

Once I started to drive the car regularly, there were some hiccups once in a while which I just thought was some more that came loose. For the last three years it has been very smooth and the mpg's even got better.

Just a reminder - the 300SEL runs high rpm. ~3000 rpm @ about 60 or 65!

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2012 Mercedes E350
1988 Mercedes 300SEL
1996 Nissan Pickup
2003 BMW K1200GT