Welcome aboard, and since you are new I'll politely inform you that it is most irritating when people ask for help and don't state year and model. Is it a 6 or v8. Depending on what year you are talking about, the problem could be caused by the newly installed points. Please repost with the year, and I'd be glad to offer whatever help I can as a 30 year MB mechanic.
Auto Zentral Ltd.