I noticed on cylinder #1 that one of the spark plug boots just seemed loose on the plug. The boot also had a small crack in it. I decided to cut the old boot off and put a new one one (I had a spare one handy). What I found was that the spring clip that holds onto the spark plug terminal had cracked in half. Hard to see here, but there are two holes in the terminal and a spring steel clip reaches around it and has two little dimples on both side that fill the holes and hold onto the terminal.
