2oo1XJ

The other day I was driving and noticed my check engine light was on. Ran over to AutoZone to get a code pulled. It was P0305 a cylinder 5 Misfire. My first thought was to change to spark plugs and go from there. I have a 2001 XJ that has a coil pack. Anyways, pulled of the coil pack and replaced the spark plugs no problem and put the coil pack back on. Started up just fine and drove it around a bit. When I was on my way home i noticed the check engine light was blinking, which after a little research I found out that means there is a massive misfire? or something along those lines. Just coming on here to get a second opinion, maybe i missed a step while doing to change out. any help and advice will be appreciated!