All the prvr does is remove vacuum from the pressure regulator on heat soaked starts to supposedly stop vapor lock. Its deleted on mine as well and I have no such issues. Does your car stay lean even in boost? If so who tuned your car? If it goes to stoich or lower under boost the 1 minute lean at idle and easy driving is normal. Things I would check for the starting issue would be the MAFS connector and voltages, your airfilters, and plugs. Had a Z once doing a similar thing and the MAFS ended up having oil on it from an over oiled intake.
......And just as they're about to catch me.....Twin......Turbos......Kick.......In!