1999 Chevrolet Suburban

Engine Performance problem
1999 Chevy Suburban V8 Four Wheel Drive Automatic 130000 miles

My 2500 series engine (5.7L) stumbles when you reach about half way on the throttle. Also stumbles at slow speeds after sitting for 15-30 minutes, then that goes away quickly, but the first problem is constant. I recently changed the plugs, plug wires, cap, rotor, and fuel pump. No change whatsoever in the problem. It has federal emissions. Any ideas?
Mi problema
March 6, 2010.

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