I was wondering why my recently acquired [and recently tuned up] 1989 300E was idling poorly and had next to no power [driving around the block was an expedition].

Over the past few weekends, I've checked for vacuum leaks, electrical gremlins [the infamous OVP relay] and not come up with anything obvious.

I decided to look at the spark plugs - and I discovered the main reason the engine seemed to be running on two cylinders is that is was. Four of the leads had wiggled loose, and could be pushed in quite a distance before feeling the threads on the plugs engage in the sockets.

The car runs much better on six cylinders, but after a short test ride [30 miles or so - the odometer is strictly decorative] I noticed the idle was rougher, and there was hesitation starting off from a stop. After the engine cooled, I checked and the number 2 and 4 wires were loose again.