PRESSURE DEY! THATS MY PROBLEM I HAD 4-5 months ago and now it has reached the stage of not starting properly and if it does, not revving out enough and shutting off when putting it on drive.
Also, what can cause that is fuel pressure problem(bad pump in tank or up front) OR check your fuel feed lines to the front pump and see if its leaking, any tiny leak will cause that as well.
Also, plugs, make sure you using the correct plugs. Check coilpacks as well, these cause a problem also.
If all else fails, then its the big black box in front. This is what has caused my problem and hopefully when i collect the car January i can plug in the new one and see if it fixes the problem.
Damn GDI thing making me more angry than angry birds, 5 months or more its been down.
By the way, is it GDI or non GDI?