OK, good. Reading the error codes on the older mercedes do NOT use the traditional OBD-1 connector to read codes, so your options are to start throwing parts at it, buy an aftermarket mercedes OBD-I scanner (and figure out how to use it since it was made for technicians), or have a professional shop diagnose it. It does sound like an ignition coil, but that is NOT a guarantee, or even a recommendation. Some parts stores still test coils, but that is just a shot in the dark since we do not know the OBD-1 trouble codes that are stored in the vehicle memory or pending.Call around to parts stores and see if they will test your coil if you remove it from the vehicle, or look around for some of the "old-school" quick/easy ways of doing it yourself. Really simple. If you do not feel comfortable doing either, a professional shop specialized in German/foreign vehicles is your best bet. Let me know what you find.