I own a 1987 240GL with 326,000kms. Two years ago I had trouble with the electrical connection on the air mass meter(Bosch), the car would suddenly stop if the connector came loose. This was fixed by buying a used plug & soldering the six wires to it. More recently the car coughs & splutters particularly when driving slowly or stopped at say traffic lights after the engine has warmed up. After a going down a long slope with foot off the throttle & then trying to accelerate up the other side the engine will misfire. Engine runs smoothly at touring speed. Any ideas? I feel it again involves the air mass meter.