Why is #4 cyl misfiring after new plugs,coil. if I unplug 4 coil nothing happens on 2008 Nissan Altima

It just started running rough. #4 plug was real black and gummy when I replaced it. Every so often there is blow by smoke when he starts the car. if I unplug any of the coils the engine nearly shuts off, but if I unplug #4 nothing happens. Is it the fuel injector?

Asked by for the 2008 Nissan Altima
1 answer 2 comments
Compression reading was??... Noid light flashing when testing # 4 injector pulse??... # 4 coil actually producing spark when tested with spark tester???
I'll have to get these checks done. Right now the check engine light flashes on and auto zone stated the code said #4 cyl is misfiring.
Yeah, got to do some more testing to get to the bottom of this one!... Start with the compression test.!... That's the main thing at this point!