Hey Folks, 

  
DIY mechanic here with a 2013 Ford Focus SE, 108k miles, automatic transmission. I had a rough idle, so I thought to change out the spark plugs and coil boots. I found two things I'd like a better opinion on. 

  
First, the spark plugs may have oil on the threads, though I'm not 100% certain because it may be residual antiseize. See photo. The central two plugs definitely had oil on their ceramic tops, and I could see spots of brown oil in the their wells. When I blew some air down into the central wells before removing the old plugs, a few hard, brown pellets flew out. Maybe carbonized oil? I don't know. 

  
Second, on the driver's side ignition coil, the plastic holding the coil threads / bolt in place  cracked. See photos. Looking closer, I saw some prior mechanic had snapped it. Then, he covered it with some kind of brown adhesive and bolted it back in. When I went to screw it back in, it was already fragile and cracked quickly. 

  
Questions: 

1- I've read the recommended fix here is a new engine valve cover, with new gaskets included. Anything else I should consider changing ? 

2- What is the short-term fix for the cracked bolt? More adhesive? 

3- Is it safe to drive this thing temporarily with a loose ignition coil? 

  
Thank y'all! 

Coil bolt mount cracked; oil on the spark plugs.