So i have a couple major issues that just arose out of nowhere. a few weeks ago i changed all 12 of my spark plugs, and for a while it was running great. then i started hearing a strange noise coming from the engine. it sounded like a loose belt that was flapping around, and the noise was consistent to how the engine was working. I couldn't locate the sound, and after a few more days it got worse and worse. one of my friends whos a mechaninc connected his computer to my car and it said "P0301 cylinder 1 missfire"

So we started checking everything. we switched the coils and wires to the opposite cylinder, but same noise. at this point we thought the sparkplugs were defective so i ordered 2 plugs for that cylinder. today i changed those out and it was the same result with same error code.

what could it be that im missing. Also dont know if this is significant but the sparkplug smelled a little like gasoline.

thanks for any advice.