So I think I've begun to narrow this down through a bit of my own research. I'm 22 and kind of new to working on cars so there's a lot I still don't know and want to get some other people's thoughts before moving forward with buying parts and getting to work. I try to be as detailed as possible here with what's been done so far and what I've come to find.

I have a 2015 A5 with the 2.0T TFSI engine, 130,000 miles. bought it at 105,000.

So for starters, a few months I had been dealing with a sometimes rough idle, which about a week ago turned into consistent misfire in cylinder 2, swapped coil, misfire stayed. Spark plugs were pretty disgusting, probably never replaced, so I learned how to replace all of them. Problems Solved- for a few days...

Now I no longer have any rough idle, though my engine sometimes misfires sporadically once or twice a second when opening the throttle past about 75%. In doing research I have learned that oil in the spark plug holes and on the ignition coils is not typically normal (which was the case when replacing the plugs but I didn't know that was abnormal at the time) It's on all 4 coils to differing degrees, dried oil higher up and fresh oil dripping out of the bottom of them. According to my older brother the old plugs were oil fouled (I'll attatch an image of the coils and old plug). During more testing it was mostly cylinder 4 misfiring and when swapping the coil to 3 it did follow, so maybe those need replacing, but obviously I have a larger issue here.

So far research has led me to think the diagnosis would either be bad PCV valve or bad valve cover gasket. I would go right ahead with one of these but I'm tight for cash at the moment and would prefer to land on the proper diagnoses before moving forward. I'm hesitant to say it's a bad PCV valve because the idle is not rough, it's not making a whistling noise, and the oil fill hole sucks air pretty hard when the oil cap is removed. I tested the valve cover gasket for leaks by spraying starter fluid around the outside of the engine where the gasket would be and listening for RPM rise, which didn't happen.

Where I'm at right now is that maybe the PCV valve is bad in some way and I should just do that, or that the valve cover gasket is bad only in between the cams where it disects the spark plug holes and oil is getting in there, though I suppose maybe it's unlikely this is the case for all 4 holes.

I would apprecaite other people's thoughts and feedback on this. Maybe my lack of expertise has me making assumptions or perhaps I've got tunnel vision and it's glaringly obvious it's something else.

First image is coils, second is old plug, the third and fourth are a new plug I checked yesturday.

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