I bought a 02 Audi A4 with the 1.8t and the kid who owned it did a lot of work like Switching the Motor and trans and open air intake and left hoses clogged up for an Evap delete and or the purge valve smells like fuel vapors when the cars running in it and isn’t that good on gas even though it’s pricy now and do I need to use only 93 because I’ve used regular and 89 middle grade not always 93? So please explain to me what I don’t know or what was removed that’s why because of the evaporation system right?