hello, my buddy owns a 2001 impala base model equipped with the 3400 engine. the engine has no mods. currently the car shifts fine and accelerates but during acceleration it putts then shoots off. car has 135,oo miles anyone experience this?

We changed plugs,wires,pvc valve, fuel filter, cleaned injections, and air filter any other suggestions...the mechanic suggested he run 89 octone gas now

Have you checked the fuel pressure? The fuel pump may be weak and not able to hold pressure under acceleration..

Never thought of that...that may be a good idea. my buddy also told me he has taken it a shop and one shop said it may be something in the trans while 2 others said the trans is fine.

It don't sound like a trans problem to me. Sputter/dying is usually spark/fuel related. You can try checking the fuel pressure regulator too.