I had my g37s coupe 2008 it is fbo e85 and 91 tuned by admin tuning and it was leaving me stranded everywhere 3-5 times until I decided to take action and repair the problem I had a mechanic replace all fuses of the car including the alternator fuse and replaced the alternator and battery and car started and doesn't die anymore but the problem now it gave me codes P2123,P0643,P0122,P0227 and the driver side throttle body making a noise and pedal doesn't respond when I try to accelerate, and car starts right up every time but idles at 500 rpm’s but it’s funny how right after I replaced the alternator that problem popped up if anybody can please help me I haven’t used my car in months thank you so much in advance.

 

Double check your grounds!
Double check the TB wiring.
make sure you aren't overcharging
Is you alternator in "smart mode"? Or Did you clip the pink wire?
If "smart" are all your grounds going through the load sensor ring?

 

here is the sound it makes I don’t know why it does this and the accelerator when I press it dosent respond or if it does it turns off the car and it has the slip light and vdc off and cel on and throws those codes I told you, and idles at 450-500rpms and I just order a new Throttle body 2 days ago you think it’s not the throtttle body but rather the wiring?

 

Just telling you to cross some things off the list.
troubleshooting 101, start with the simple stuff.
did you reset the TBs? Idle air relearn

 

yes I had my mechanic with his 3500$ scanner try to relearn and it wouldn't finish relearning and I also tried to do it manually and try disconnecting the negative terminal nothing worked still idling at 400-500 rpm’s and has 3 lights on vdc off and cel and slip I don’t know what’s wrong I ordered two new throttle bodies with the sensor but I feel it’s going to be electric grounds or a electrical short or something because my throttle bodies were fine and everything before replacing the alternator what would you do my throttle bodies are coming in a week and when I try to accelerate it shuts off.

 

If it all started with theAlt swap, id start retracing the steps taken there.
Trace the alt wires, double check output, etc.
Disconect it temporarily even. See if the relearn will take with it out of the system.
Did you disturb TB wiring when Alt was replaced? Shouldn't have had to, but if so...