Occasional sluggish acceleration after start up.
 

Have a 2013 370z automatic with touring package. Sometimes after I start up engine (doesn't seem to matter if it's hot or cold, or I let it warm up a minute or two) I'll notice that when i step on it, I'll get a bog down, and a downshift to a lower gear to get acceleration. If I pull over and turn off car, wait a minute or two and restart, goes back to normal power and acceleration. What might this be...fuel injectors?