Is the car tuned?
Have you checked for boost leaks?
The car came with a tune. "Olympic Motorsports Stage 3 tune" Not sure how it was tuned or how reputable that tuner is, but i switched over to a OTS tune from COBB. Stage 1 tune, and i do not really go into boost that much as i want the car to be in top shape before i start to push it.
I have checked for boost leaks, and found several. I have since replaced all the vacuum hoses, re-circulation hose coming from the BOV, and the silicone on the FMIC piping. The car ran way better afterwards, still the LTFT issues though. I tried replacing the O2 sensor since i do have a new O2 sensor, but it is stuck on there! I noticed the down pipe ins't OEM either, it looks like a cheapo ebay down pipe, but no exhaust leaks or cracks.