I own a 2003, 6 speed 350z. Long story short, after owning it for a week a fuel pressure issue arose. The car almost feels like it hits a limiter once it reaches 4000ish RPM and that no more fuel is being injected. At one point the car began stalling out on its own but after I replaced the fuel pump the car has no longer stalled out. The same issue remained however; when under power the car just loses fuel pressure and doesn't want to keep accelerating at around 4k RPM. Any idea what could be happening?

 

Check the fuel cap yet?

 

Check your spark plugs

 

Is the vehicle throwing any codes or check engine light? What kind of aftermarket mods have been done on the car if any? This could be caused by any number of things. Have you verified the fuel pressure is within spec at the injector fuel rail? Have you replaced the fuel filter?
-Icer