Hi, my wife's C200K estate has developed an annoying fault. It falters when idling and threatens to stall. Its done 130,000 miles. The engine light lit up and merely reported a misfire on cylinder 1. I cleared the codes to see what comes back - it occassionally reports a problem with the throttle body - but its occurance is less often than the car is logging the misfire. Today I have swapped the coil pack and spark plug with cylinder 2 to see if it moves. Over a year ago I checked and found the car did have the oil from the camshaft sensors problem and I fitted a new down stream sensor, cleaned the loom, fitted the intermediary loom fix and checked the ECU end which was completely clear. It was not exhibiting the problem then - luckily I read the forums so reacted before thre leak was too bad. What I did not replace at that time was the upstream sensor - is this a posibility? I had purchased a NGK OZA659-EE24 but when I went to look today I am sure the wiring attached is too short. So any input on what might be contributing to the problem would be appreciated and a secondary question is where is the connector for the upstream sensor please - I have traced the wire from the upstream sensor and it disappears around the back of the engine above the transmision - where does it actually clip?