My car (2003 z performance trim) sputters violently between 4000-4500 rpm...people told me it's the maf sensor... I replaced and still problem... so now Nissan told me it could he bad catalytic converters... would bad cats cause that? Or should I check out my throttle position sensor .... any help would be greatly appreciated....

 

have you checked to see if your car is throwing any codes?

 

I had a code and some guy checked it, didn't tell me code and left never to be found.. didnt answer my calls or show up to work.. so Idk what the code is

 

that'd be the first thing you need to figure out. take it to your local pep boys/autozone/o'reillys, etc. and get them to tell you what the code is.

 

I brought it to Nissan and they said they could not do anything because I did not have a cel

 

I'm pretty sure you can have codes and not throw a CEL. Take it to a different dealer. The code is more than likely related to the sputtering issue.