Smoking 190e
 

I have a 1985 190e 2.3 8V with 160K on it. It is a litle laking in power and starts a little hard, but otherwise runs and drives well. This morning, halfway to work (about 13 miles into my trip) the car started smoking at a stop light. Now it smokes whenever it is stopped and smokes when I take off. It does not smoke at all while the car is moving (atleast not that I can see). I tried letting off the gas and coasting for a bit then applying gas again and it does not smoke then either. This is a sudden development. Anybody have an idea. The car IS due for an oil change, could that be the cause? Any help will be much appreciated.