Mistake #1:

Not further investigating the problem. Instead of looking into it, you just replaced the spark plug and figured that would fix it. If you pull out only HALF OF A SPARK PLUG...where the FUCK do you think the other half was? You should have parked it and took the shit apart right then instead of thinking you fixed it by just replacing a spark plug.

Mistake #2:

Thinking 'octane adder' does anything