1997 Sl320
 

Just did a tune up. Coils, plugs, wires. Starts immediately most mornings. After that, the car is difficult to start...and now idle seems to be a little rough at times. Was this way before the tune-up. I did a tune up because there was a misfire on #4 cylinder. Any ideas?

If you have an ODBII reader you can get the code and that will tell you if you have a fuel or spark problem. The coil packs are known to be problematic, if a coil pack fails replace all the wires too, you can buy them on this site, MB only sells the components for assembly. If not spark and fuel related check the wires to the injector, the connection, all around it. if no problems replace the injector. If you have any other problems such as smoke in the exhaust, or oil in the coolant it could be a head gasket leaking and causing the mis-fire. With a well maintained 104 engine, I am going to say it is the plug wires or coil pack. and secondly the fuel injector and or connections. A proper code will tell you exactly what the failure is. Good luck!
Brian