1996 Chevy Tahoe Not getting enough fuel

Engine Performance problem
1996 Chevy Tahoe V8 Two Wheel Drive Automatic 179.00 miles

We have a 1996 Chevy Tahoe that quit running, and we replaced the fuel pump. Now it runs at an idle but runs very rough when you throttle it. Did a tune up, cleaned the injectors and all, replaced the fuel filter, had it hooked to a computer and had several problems diagnosed, and replaced those parts, but it still will not run right. Idles fine, but when you drive it, it spits and sputters and has no power. Someone suggested maybe the Cat. Converter was clogged up, So we replaced that. Now we are about "Tahoe" broke. Was most recently told to check the fuel regulator, doesn't seem to have one. Would you know where to look for it? Can you offer any further HELP!