2010 MINI Cooper still running rough

i have a 2010 mini cooper and when i bought it, it drove a little rough, but i replaced the spark plugs and ignition coils, i found a little oil in 2 of 4 spark plug wells after addressing all that it ran a little smoother but still rough, and once in a while it will stall out and i have to restart the car, any ideas what this might be?

Is the check engine light on? How many miles on the engine? Do you need to add oil regularly?

fuel pressure, compression, and fuel trim measurements are needed.

And how did you address the oil in the spark plug wells . . . ?

have you perfomed a compression test