Weird Meta Mystery Thriller with PI in disguise with mustache and hat. Read 2013-2014.

[Chris]

I read this book in 2013/2014.

There was an investigation being done and the investigator wore a disguise with a big hat and a strange mustache. The writing was very self-aware, I remember the end of one chapter being something like "they had to run" and then the next chapter was just the words "they ran".

The pacing was weird and the writing style was strange. I think the cover was mostly red and it may have a burned/burning corner.

[Kris]

Chris, what is the story's time period and location?

Can you describe the mystery?

[Kris]

A long shot - John Dies at the End by David Wong?

Google Books preview: https://books.google.com/books?id=Yu3...
There are different cover images.

Google search of Goodreads:
site:goodreads.com "mystery" "PI" strange writing meta

[Chris]

I think it was set in the USA and was a contemporary setting around the early to mid 2010s