I have a 1991 Mercedes-Benz 300SL-24 (R129). The car has about 40,000 miles on it, but is ten years old. Of late, the car has been very difficult to start once the engine is all warmed up. After parking for twenty minutes or longer, it will require several cranks before it actually starts, and even then it misfires for a few second before idling normally. My friend's W124 300E is also experiencing the same problem.

I have replaced the spark plugs, and ignition wires. I am wondering if the ignition coil is old, since it has never been replaced.