I just changed out coil packs and spark plugs. Turns out the coil pack anchoring/retaining screw won't tighten... not sure if it's the screw itself or threads in the valve cover. Coil pack is mostly tight but not as much as the other 3, does wiggle a little. I drove it for like 15 to 20 min, actually drove well and idles so smooth (feels like the engine isn't even running).
Was just curious about the risk of driving with it not completely tightened. Will it eventually start misfiring or randomly stalling?
Probably not. If the screw seems loose, wrap some Teflon tape a few times around the threads then snug it down. Hope this helps.
Actually, a permanent fix would be to tap out the hole with for the next largest sized screw and install a new one. You could also just get a new valve cover, assuming the coil packs are attached to that.