I have read in other posts some thing like "engine running rough".
I don't understand this correctly.

Lets look at my problem quickly.

When I stop at light or some other place I feel this strange grrrr sound. It wasn't there previously. There is slight really slight vibration.. You feel some thing ist right with engine...
The idling is fine 750rpm..
I don't now how to express that sound is like.. some what similar when some dogs dont like they make grrrrr sound.... That is funnyy.. but
What I don't know is whether this is what usually known as engine running rough ????
Other than sound there is no other noticable problem as of yet...
thanks