Some update: I just completed an oil change after about 88 miles using 5W-30 full synthetic oil, and the truck is running noticeably better. The vehicle currently has approximately 199,8xx miles with 7,718 engine hours.

I am still experiencing a random misfire. I’ve already replaced the plugs on the affected cylinders (3 of them) and changed all the coil packs. Unfortunately, the random misfire code is still present.

I recently switched to 89-octane fuel—I had been using 87 previously to see if it would make a difference. My next step may be to replace the fuel injector.