I have an issue with a 2005 c230 Kompressor. When I'm in drive with my foot on the brakes it seems to be the worst. I was receiving a code p0620 Generator Control circuit and replaced the alternator because the voltage regulator failed. I still have the same problem. I noticed I can make the rpms drop when i turn on anything electrical. This happens while in neutral as well. I turn on the headlights or ac and I can watch the RPMs drop. Also, can make RPMs drop by rolling up the windows. This is very annoying being its the worst with the ac on. Basically, it wants to sputter at low RPMs when there is an electrical load. I noticed it makes the RPMs drop and the motor sputters/vibrates when turning the steering wheel.
Please, any input is much appreciated. It's driving me crazy every time i am at a stop light I have to pop it in neutral (Automatic Tranny)
I replaced the alternator today hoping that it would fix the problem since the voltage regulator tested bad before.