Hi I just want to ask why is that my 89 Civic LX wont go past 4000 RPM even if I push the pedal at full throttle on highway?

I think when it was on idle and I try to rev it up it goes past 4000rpm, but when I drive and hit the throttle full down, it wont go past 4000 RPM...why?

 

Is the engine in proper tune? The correct spark plugs? Ignition timing? Cam timing? Valve adjustment? Is the air filter clogged up? Does the fuel pressure drop off at as you rev it?

 

Did you do a recent T-belt job on it? Reason why I ask Is because when I did my last swap, the d-bag that I let set the timing basically 180'd my crank. I was curious why after 3 grand it had no ***** behind it and by the time I figured it out.... well boom.