Misfire help on '01 SE

Have '01 SE. yesterday I got a misfire in cylinder 4 (code P0304) the service light blinked on and off 3 to 4 times than stayed solid. changed plugs and boots about 1 to 2 months ago, didn't change coils and they r not in the best shape but didn't have money to replace at time. so I replaced the coil for #4 and it still runs rough with code, plug has some ware but looks fine. Any ideas are appreciated, Thank You.

1) Do a visual inspection on fuel injector signal, and ignition signal wires going to cylinder 4.
2) Make sure you are troubleshooting cylinder #4.
3) check compression on cylinder #4
4) If an injector gets a signal + clicking sound, doesn't mean it's good.
5) Roll the injector to another pos.
6) Don't forget to reset CEL.