About 3 months ago, my engine (2010 Silverado 5.3L V8 LC9) began to run rough and the check engine light came on. I checked the code and got a P0304 - misfire in cylinder #4. When I got home, I pulled the plug and found it badly fouled as show in the attached picture. I went ahead and replaced all the plugs and wires at that time. This past weekend, I pulled the spark plug from cylinder #4 to check it. It's not nearly as bad as the one pictured, but comparing it to a plug in a different cylinder, it seems to be building up gunk on the plug faster than the others. Additionally, I've noticed the the past 4-5 months that the truck has been burning oil. I don't know if they're related, but I'm throwing that in here also. From reading, it seems there are a number of potential issues that could cause the plug to foul. I've looked at pictures where they show different types of fouled plugs and the potential causes, but it's not obvious to me which category my plug falls into. From the attached picture, does anybody have suggestions of what to look into?
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