When I start my car(04 sedan 5at), the rev needle spikes to under 2k, then dips to 1k and when it does, the engine sounds like its going sputter and stop but recovers to normal after the needle goes back to 1.75k(just under 2k). Any ideas on what this could be??

 

clean the throttle body.

 

If u do clean it make sure u do the idle air reset procedure..

 

There's all kinda things that might make your Infiniti freak out like this, try an idle reset first. Members will remove the negative side of the battery over night thinking it will clear an issue when in fact it makes the ECU forget why it's there....Gary