I brought my 2003 nissan 350z in for an engine light and a rattling cadalytic converter. When I got the car back it wouldn't accelerate like it did before, like something is constricting the air flow. I took it back and didn't bother to check the o2 sensor or the converter they replaced, and insisted it was the electronic trottle body and are now out another $280 . The problem is still there and can't express how angry I am about it I feel like taking the dealer to small claims court if they don't get it resolved without more money out of my pocket

 

why 2 threads?

 

Possible your old cat was blown out,gutted.Thus,you were driving with pretty
much a smaller test pipe.After you got your car back,is it quieter?I mean,was
the exhaust louder before?On the throttle body,again it may need to be reset.
I'd want to see the old cat.

 

The converter was working fine but had a rattle I couldn't stand so I bought a new one from nissan and they put it in, also but an o2 sensor in, ever since I went to the dealer I had horrible acceleration issues...the rattle is gone now I have poor acceleration

 

why didn't why check the parts they put in instead of looking for other things it could be and having me buy a new throttle body when I didn't need one

 

Im new to this, I didn't know if everyone could see it ...