won't rev over 4000rpms

[holshotracer]

i swapped out the a4ld for a 5 speed and now have a problem. when stopped or parked the motor will rev to the rev limiter. but when driving it will only rev to 4 grand and then the motor cuts out.
thinking that it was the difference between the auto and 5 speed computer, i borrowed one from a 5 speed. the truck barely ran. so i put the auto computer in and been running it since. what could be causing this it as me stumped.

 

[X-North]

change the fuel filter, spark plugs ,wires and air filter...normally if you have less spark,fuel or air the engine lose power so it wont rev correctly.

 

[holshotracer]

the plugs have about 8,000 miles on the and the wires are fairly new. the fuel filter is brand new.

 

[Turdle]

Check engine light?

 

[CheapThrillEX]

http://www.explorerforum.com/forums//showthread.php?t=191605


it is his truck i was posting about


it cuts out like a rev limiter not a poorly tuned engined