I own a 1987 MB 260E with about 83k miles. I have recently noticed that occasionally the O2 sensor light flashes on for a short period of time (less than a couple of seconds) and the car tries to stall out or runs rough. The problem occurs when dirving at any speed and when stopped at traffic lights. I'm not sure if it occurs when parked. This problem seems to occur when I have the heater turned on.
I first experienced the problem several months ago. It has only happen about a half dozen times. I did not experience the problem for about a month of driving with the heat and A/C controls turned off. Last night I turned on the heat on my way home and the problem started within about 3 minutes. It went away after I turned off the heat.