Help Me! ... 300ZX will not accelerate .. diagnostics says fuel pressure regulator ... changed it and car runs the same ... i think its the ekg emmsion control ... can someone give me some sound advice!

 

don't understand the rich or lean question ... the engine i believe requires high octane gas and I generally keep that in there ... the reason why i think the problem is the egr is because i have tampered with it a few times and the car would start running like a rocket (no problems) ... then it dies back down to and starts having very slow acceleration again ... it kicks in and performs well like once a week but lately it has not kicked in at all ... i was also thinking it could be the fuel injectors? Any advice?