Hi , hope you haven't bought a load of trouble, from what you describe i would first be looking at the fuel pressure which will need a code reader displaying live data to get it from a facelifted model, no schradar valve on the fuel rail.
It should be between 30-40 psi or mine is at approx 250 KPs, if low this could be down to a clogged fuel filter or the filter housing comming loose.