Zach Opfer

I have a 2008 Ford Fusion 2.3L 4 cylinder, manual transmission, with 163k miles. Check engine came on last Friday and car started shuddering really bad, idling low (about 500 rpm when at a dead stop) and reduced power. Took to O’reillys and they said it was throwing the P0304 code, which is misfire on cylinder 4. Pulled the coil, no sign of melted plastic. Pulled the spark plug (all plugs were replaced roughly 2 years ago) plug looks fine. I went ahead and replaced the coil pack on cylinder 4. Runs about the same. Here is where it gets weird. When I start the car from a cold start, like in the morning heading to work, or on my way home from work, it runs just fine, has full power no shudder. But if I stop, turn off the car and restart it, once it has warmed up a bit, it goes back to running like crap. The check engine light has remained on for the duration of all this. I just added some injector cleaner today to see if maybe that was an issue. Any ideas? Thank you all.