hello,my car is running very very rough is it possible my cats are going bad at 65k?hard shifting bad jerking at speed bad bad rough idle i goose it at idle it sounds like its almost going to backfire-but inside the cat weird low sound,i thought maybe trans and took it to a trans shop they said 7k for a rebuild,i really do not think its trans if it runs the exact same way at idle as it does when in gear,anybody?