[Z28allday]

when i go from from low rpms and try to floor it it feels like im not getting enough air flow (power) till it clears up on higher rpms and i also notice when i get on it at the same time the shifter vibrates till it clears up it happens in any gear from lower rpms to higher rpms any idea what this is already changed all of the brakes from calipers and rotors to brake pads and break lines also changed out ignition wires spark plugs fuel and air filter...i think it might be the cat which has all of those things in it that proll got stuck all around it? and when air flow comes through its not flowing through properly somehow? any ideas can someone elaborate please???????