A couple weeks ago, I was having trouble removing the plastic sparkplug connectors on my 1995 C220. I finally did get them off. I know this is a fairly straight forward job for most, but I would like to share "my how to" experience. Here are the steps.
o Remove access panel (3 socket head screws)
o Remove air intake pipe. Loosen hose clamps on rubber boots. One on each side and slide rubber boots off. There is also a small rubber hose to be removed. Once the rubber boots were slid off, I just placed the air intake pipe aside without completely removing it or disconnecting any electrical connectors.
o Sparkplug connectors were hard to remove. I had to twist and wiggle to free the rubber seal against the plug. Finally with alot of force the connectors came off.
o Blow out the sparkplug wells with compressed air to make sure no debris falls into the sparkplug holes as the plugs are being removed.
o The sparkplugs were removed with a 16mm long socket. I used the sparkplug tool from my sons BMW 318i tool kit to hold and remove the sparkplugs from their deep wells.
o New spark plugs Bosch F8DC4 (0.8mm gap) lightly coated with anti-seize.
o I used the same BMW tool to hand thread the sparkplugs into their threaded holes. Very important to hand thread to prevent cross threading.
o Sparkplug torque 15-22 ft-lbs (20-30Nm). Bosch manual suggests that you reduce the torque by 30% if you use antiseize.
o I used 19 ft-lbs
o Replace every thing in the reverse order. I put a slight amount of rubber lubricant on the hoses to make them slip on easier.

You make the search function FUN! Thanks for this. I've had a set of plugs sitting in my trunk for over a month now. Your writeup has encouraged me to get on it!

it was bound to happen to someone, but i think i'm just overthing it. Upon removing the plug wires, i noticed they were marked '1'-'4' so i didnt make any effort to check the order.

I'm pretty sure they were sequential from 1-4 (front of the car to back). Is this correct?