Mis fire..Spark plug?

[Mike]

for some reason,last time i used my car (2 days ago)it was fine.went to use it yesterday and it popped and misfired (Bear in mind my gasket has gone and 1 plug gets caked in oil) instant thought was down to the plug/s.
I took um all out and cleaned um (3rd from left was caked in oil) BUT the first from the left had bits of plastic inside the tube that had come off the plug :/ i tried to get it all out with long nose pliers.Once all cleaned,put them all back and it still misfired. So i left it running,unplugged each plug 1 by 1 and it went to stall apart from that first one,it didnt make any difference :/ is that down to the plug? Hope havnt got bits of plastic in the head.But saying that,the coil pack covers it over anyway.

 

[Mike]

sorted

rather than buy a plug i changed the coil pack for a spare i had,still made no difference.So went out and bout a new plug (EGK for 3.99) and its back to normal.God knows how my plug got like this tho v

even tho the plug was in that state and the rubber pipe fit straight over the plug,it should have made no difference? strange.