To all those spark-cover-less guys out there

[Fusion]

Check your 6th plug hole. My engine started stuttering and I thought a coil went bad but soon learned that there was washer fluid around the 6th plug. Probably a leaking washer line since the pass. side takes longer to spray.
Doh!

[bimmer630]

Yeah man, I had some water build up in my spark plug holes, then freeze overnight... the car would run great until the ice melted, about halfway to work.. then start misfiring.

Got a cover on there now

[Fusion]

Mine ran fine until the engine got hot and the fluid (although very little of it) started to boil. I guess it then condensed up in the coil plug.
Glad I found it, I was about to buy a new coil.

[butters]

Pro tip if you're going to run without it - careful opening a wet hood. I noticed when washing that opening up the hood often results in a drip right onto that location. Covered it since.

[Mr. Schwarz]

Unsure of actual location? Picture? I've been battling a misfire issue.

[Fusion]

Cylinder nearest to the firewall (in my case).
Take out the coil, get a good light (used iPhone LED) and look closely for liquid around the sparkplug.