Are you having misfires or has the engine recently started sounding like a V8?
 
 
Then it's definitely the ignition coils. There is a grouch among the 6 ignition coils that is no longer playing along. Unfortunately, the ignition coils on the Nissan 350z are somewhat vulnerable, as you often read about in the forums or in various groups.
 
Also known is the error code P0305, which indicates that the ignition coil needs to be replaced.
 
 
TIP:
 
We also had this problem a few times ago. There we carried out a quick test and removed the ignition coil connectors while the engine was running and observed whether there were any changes.
 
Changes = Ignition coil OK
No change = ignition coil possibly defective not OK