I have a 1991 300E2.6 that had the same problem which I approached differently. I purchased an after-market ignition... Jacobs Omni torquer. It could probably ignite vaseline... I can't get the key off fast enough. Before it took a 2-3 sec crank or even 2 cranks to start. I also got a 2mpg boost in fuel economy.
I also had to replace the stock wires with a silicone plug boot. The unit was literally blowing the stock spark plug wires off the spark plug every few hundred miles; the car would start missing and I had to open the hood and reseat the wires.

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