changing the spark plugs on my 95 E320. It was loud at first. I checked the spark plug wires and started the car again and the sound is still there but less loud. Noise increases in speed when engine speed is increased, at the same time, actual noise decreasing. Sounds like a "clacking" sound

Did debris fall into one of the spark plug holes?? I was very careful by blowing out any dirt out before removing the plugs.
Also, it has been said that iron cores of some Bosch ignition coils are poorly glued and would need to be replaced with a different production code part.

Is it possible to damage the leads/coils when servicing the plugs??

the car has 56,000 miles.