05 Wrangler Unlimited 4.0L valve cover gasket

My wife's Wrangler (80k) is leaking oil from the valve cover. So off it comes. There's a lot of sludge in there. In fact, the holes between valves (for each pair) are full of sludge. I assume these are oil drain holes, but don't know for sure. I want to clean them out but want to be sure that's the right thing to do. My guess these holes got blocked with sludge and promoted the valve cover leak. Any advice on cleaning up the top of the head?

Also, getting the valve cover off was a PITA because of that darn plastic cover over the wiring harness at the back end of the valve cover. It doesn't seem easy to completely move that plastic cover out of the way because the contained wiring harness splits on both ends and goes everywhere. Any advice on making reinstallation easier?

Well, those weren't drain holes...they bottomed out. Just cleaned out the sludge.

And I was able to maneuver the valve cover back in place.

My only remaining question is if I should run an oil additive to clean out some sludge. I've never done that in the past, but it seems like this Jeep has much more sludge than I've seen with other vehicles.

You'll want to shorten up your oil change interval, use a better quality oil, or both. What OCI and oil are you using?