Originally Posted by SINISTER

So you cleaned the throttle bodies? Did you follow all the instructions? Because allot of people get a higher RPM because they did not research it completely...

Here is some information that I researched and put together when I had a G37, never had the higher RPM and recently did my 370z also with no problems...

In studying the service manual very closely I discovered some things that are not mentioned that may or may not make a difference in the cleaning of the throttle body and then the associated problems with idle etc. Note: Normal Idle is 650+-50 so approximately 600 to 700 RPM.
1. Do not disconnect the battery. It does not state to disconnect the battery in the Service Tech Manual. Why I dont know. I speculate that although the power is off the the "electric" throttle control acutuator may still be monitoring/recording the position of the butterfly valves. If it is disconnected it will not monitor it and when you start the car the ECU will not like what it sees. Again this is speculation but the manual does not say to disconnect the battery.
2. When removing the Electric Throttle Control Actuator, DO NOT REMOVE anything connected to it. This includes the two water hoses and the harness connector.
3. There is a specific order to loosen mounting bolts.
Per manual loosen bolts in reverse order as shown in the figure:
4321 and then tightening it back up 1234.
4. Torque of these bolts is 8.43 FT-LB if you overtighten or undertighten could cause an air leak and ECU again will not like what it sees. (make sure your throttle body and rubber O ring is seated properly you know why....)
5. Do yourself a favor and buy a torque wrench and a Hex Bit Socket Set. Or the socket Hex bit metric 5 if you can buy independent. The whole set only costs around 15 bucks and believe me you will use it again.
6. Service manual states you MUST do the following after you clean the electric throttle control actuator inside.
THROTTLE VALVE CLOSED POSITION LEARNING : Description INFOID:0000000008161734
Throttle Valve Closed Position Learning is a function of ECM to learn the fully closed position of the throttle
valve by monitoring the throttle position sensor output signal. It must be performed each time harness connector of electric throttle control actuator or ECM is disconnected or electric throttle control actuator inside is cleaned.

THROTTLE VALVE CLOSED POSITION LEARNING : Special Repair Requirement
INFOID:0000000008161735

WITHOUT CONSULT
1. Start the engine.
NOTE:
Engine coolant temperature is 25°C (77°F) or less before engine starts.
2. Warm up the engine.
NOTE:
Raise engine coolant temperature until it reaches 65°C (149°F) or more.
3. Turn ignition switch OFF and wait at least 10 seconds.
Check that throttle valve moves during the above 10 seconds by confirming the operating sound.
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