P0301 cylinder misfire code. Already changed plugs to no avail. Any ideas?
Last week I moved from Michigan to California and towed a cargo trailer the whole way with my WJ. 2600 miles and it ran pretty darn good the whole way. 14-16 hour days. So the day after it throws a P0301 code for the cylinder 1 misfire. I changed all 8 spark plugs with the recommended Champion ones. Put everything back together, no code, ran great for a day and a half and then boom, code again. Running rough. I should note that we were dumb and didn't keep track of which coil packs came from where. We just put them aside and then stuck them back in so while it's likely they ended up in different locations, it's possible coil pack 1 is back on 1 and it's the cause. (I guess, I'm no expert)
Google searches seem to suggest it could be a fuel injector? I'm not really sure where I should go from here. What tests I can run or what other things could cause it.
2004 Grand Cherokee overland 4.7HO v8