Throttle sensor issue?

[tommyz]

Hey so after driving my car for a bit I was checking my throttle response in the garage. I'm not too sure if this is the right forum, but here goes. I drive a 2013 370z nismo. So when I am in neutral, I would tap the throttle once and quickly let go, my rpms would jump to 1.5k and stay there for about two seconds until it drops back down to idle. Even when my foot is off the throttle, the rpms would hold at 1.5k for two seconds before it goes down to 750. This issue fixes itself when I restart my car, but the issue comes back after I drive the car for a bit. Does anyone know the issue about this? I think this affects how I start in first gear sometimes as well.