Sounds like you may be running in safe mode. The first and easiest thing you should do is get the car read for codes.
A garage will do this for 50 quid or you can buy an ebay special code reader for less than half that.
You will then have a better idea of where to look for faults. You may be overboosting, underfueling, running lean or a sensor may be unplugged (n75).