You answered your own question, z32 afm, gtr injectors and a remap..
I would also put a decent fuel pump in there if you haven't already, it's quite likely that your fuel pump is dead and can't supply fuel up top.
Another possibility is that with the bigger turbo you're maxxing the afm, if it can't measure anymore air it stops throwing fuel in and hence leans out.
So, forget the FCD, get yourself an 044 pump or similar installed intank then get the z32afm fitted along with the GTR injectors and have it tuned/remapped, you will notice a HUGE difference
Oh and if it doesn't have a full 3" exhaust, put one on