Cold start Then runs rough till warm

Change Voltage Regulator located underside of your alternator, it cost about $25 and all you need is a Philips head screw driver. Park car on even surface, Disconnect battery Very Important! Jack up car make sure you use jack stands as you will be directly under engine. Locate your alternator lower right front on 190e, Voltage regulator is attached with 2 screws. Be careful when removing as it has tension and screws may go flying off. When replacing due not force the Voltage Regulator in..you may damage one of the two retractable nubs...Its kind of tricky you put in in at an angle once you feel it seated, make sure you keep pressure on until you get both screws started. Then simply tighten. lower car, reattach battery. A lot off electrical problems like battery dying, hard starting, rough idle can be attributed to this simple and inexpensive fix, its a common cause for these problems.