Somthin weird with the High RPM's

[sargent240sx]

1st and 2nd gear go ta 6000... 3rd goes ta 4500... and forth goes ta 4000...and when on highway in 5th gear.. my car will not let me go over 3500 RPMi think it has somethin ta do with the rev limiter or somthing of that sort..no matter what rpm im at.. if i over rev it my car wotn accelerate till i hit 3000...PLz help me figure wtf is goin on...!!i;ve been tryin for wks now!!!

thanks...

CaR: 90' Nissan 240sx Ka24