Have a leak down test as I had similar on my 3 door it smoked on over run and cleared under boost, I tried all the usual, and it ended up being a bit of everything but biggest concern was bore wear. Ended up with full rebuild and it hasn't really used any oil since. Expensive but worth it if keeping car. Once I knew what it was I just started collecting main parts a bit at a time then pulled engine out over winter and got it done.