Gtx di 2002

[Siinos]

2002 gtx di

Motor rebuilt
New fuel pump
New battery
New rectifier
New spark plugs ngk

Always starts no problem idles fine when I take of lack of power until I pass 4000 rpm then I have full power and I can reach 6700 rpm with full speed

Any idea of what this misfire or loss of
Power can be in the 2000-3000 Rpms range only

Thanks

 

[WaarrEagle]

I would be rigging up an in-line fuel pressure gauge to make sure that is steady throughout the RPM range.