guide

Hi everyone, sorry for yet another misfire thread. I'm looking for a guide on diagnosing the misfire, someone wrote a really thorough one years back and I've spent hours trying to find it again with no luck. Anyone able to help me out? Thanks

I am gonna try and make this as complete as possible, if you have any questions, i'll answer. So... Your 3rd brake light failed on your cup spoiler. Great you're in for a treat. Alright, first off you need to source a new one, which can be expensive as they go for about 90€ (i'm french sry idk...