Car has 140K miles well taken care of. O2 light came on about the same time that the car's engine had trouble idling. High speed (55mph) travel was no problem. When one would come to a traffic light or stop sign the engine would stop. After installing a new sensor the problem continues. Does anyone have any ideas where one should start looking? I dont want to start pulling wires or waste my time checking the wrong things. Thanks ahead of time for any help one can furnish. 1983 320is