I tried to rip a throttle unit apart to clean the TPS carbon tracks but i'm fairly sure it failed. They are definitely not a serviceable part.
Seeing Nissan want $1800 for a new throttle unit and these are failing like hotcakes I would grab any second hand VQ throttle you can get. A 350z/V35 one will fit, I am running a VQ25DD throttle at the moment due to the same fault.
If you need a hand with clearing the codes, resetting the idle or changing the throttle over, a quick search and you will find the information on here. Otherwise PM me if you need someone to do the work for you.