Update: So I went full steam ahead today. Got the new valve cover gasket ($20.99 at AutoZone), unscrewed all the 10mm bolts, pried the cover off, hey! No obvious breaks in the seal! Well, that's good I guess?
So per my advice here, I go to replace the spark plug tube seals. Might as well since they came with it. There's no obvious breaks, but it feels pretty stiff. Took a screwdriver to it. So brittle it started to break into little pieces immediately. Must need replacing then! Couldn't get it to come out, did some more YouTubing, then oh...
Turns out my seals are non-replaceable. Aaand I just tried to remove one. Woops! Three auto-parts stores later, a valve cover is in stock. $60. Put the new seal on it, cleaned the spark plug tubes that had oil (not too much since cleaning them out a week ago), and it's still stumbling.
Since switching the coil pack from 1 to 2 last time, my errors now show 1 and 2 are misfiring. But no more 3? Last time it was 1 and 3, and now one is okay? Since that didn't make sense, following the AutoZone guy's advice for now: topped it off with fuel (in case of bad gas at last fill up) then waiting until after I've driven it at least 60 miles.
Any new ideas? I guess it could still be the coil packs, but I have trouble believing they'd just decide when to fail and when not to. And the car did run better today, just not completely better. And the check engine light still blinks on startup, throwing 3000, 3001 and 3002. :/
I read a few other forums and answers here.
My 2008 Accent just hit 180,000 miles. It's been leaking oil (very slightly) for a while, but has never caused any major issues, so I haven't gotten it worked on - frankly I'm afraid of "needing" a repair that's worth more than the car.
It has had fits with misfires from time to time on the highway, but after it cools off it usually does fine again.
The other day it did it right when I cranked it. I had just filled it with gas prior. It isn't shaking horribly, but the OBD reports cylinders 1 and 3 misfiring. Did my research, tested coil packs. All give about the same resistance (~2.5 Ohms), assuming no issues there. Cleared the codes, switched the coil packs on cylinders 1 and 2. Code shows up on 1 and 3 still. Not the coil packs.
Replaced the spark plugs. Looked like they had never been replaced (bought the car used at 120k, you'd think they'd have needed to before then?). Yay! Should be issue solved.
There was some oil on the coil packs and the plug on cylinder 4 was covered in oil. Maybe I found the leak! Research shows it could be the valve cover gasket. Didn't have time to replace it while I was doing the plugs, but it's been okay until now, I figured I'd fix this then try to replace the gasket this weekend.
New spark plugs in and it's still a-rumblin'. Tried some gas treatment in case it was the gas, but that hasn't worked either.
Could it just be a bad tank of gas? Or could one of the coil packs still be bad? Or could the leaky gasket cause the misfires?
If it matters, temps got below freezing the night before the issue occurred. Really trying to figure it out, I don't want to hurt it any more before I get it fixed.