1999 Dodge Ram no power

I just changed the plugs, wires, cap and rotor on the truck because it ran terrible but it feels like I have no power with the truck. If I accelerate to fast the truck just sputters and spits and wont go, but if I ease into it then it goes fine. Also if I am driving and kick it down the transmission drops the gears like it supposed to and shoots up the rpms but once it hits around 3500 rpms it just sputters and spits again until I let off the gas. I did a fuel pressure test and they said the pressure is good so I am not sure what can be causing the problem. I should mention also that it isn't the catalytic converters because the truck has none, I didn't cut them off, the previous owner did.