Does anyone has this problem when you drive fast and when you let go of the gas the car rev to a high rpm then goes back to normal

 

Check your throttle body position sensor.

 

How do I go about checking it? If it's position right or?

 

I am having this same issue OP. took it to the infinti dealership and they said its my clutch. its slipping/not catching. I thought it had something to do with the throttle body too since it happens a lot when I don't even touch the clutch