My m8 had a probem like this only it was so bad on his that once it was started it would over fuel badly after 30secs and stall.

you need to make sure that the colours are as:

blue - cool start injector.
brown - thermo time switch.
black - aux. air valve.
green - knock sensor.
yellow - sensor under inlet (cant remember name but its also yellow )

if you have these connected different it might cause your problem.
if you think that your cold start injector is not grafting unscrew it out of the inlet and see if it sprays fuel out (but watch your eyes it can go everywhere )
and if it aint swap the brown inlet sensor for a different one xr3i also have them