2004 Chevrolet Silverado 1500 5 3 Check Engine Light Comes On Reduce Power

i have 2004 1500 5.3 and the check engine light comes on then engine reduce power comes on .then other times light does not come on and the engine runs at high rpms (2500 or more) i have changed throttle body, fuel petal position sensor, throttle control module ,mass air flow sensor, and none has fixed the problem .what is my problem .