Can't race my G .. Just 2000 rpm
 

Alright... yesterday i was cleaning my car thorttle body and for some reason I desconnet the battery Big Problem !!! Now I can't even have my car more than 2000rpm and still looking for a reason !! I hope you guys know about this and help me out with my car! G37s 2008 coupe

Sounds like your car went into limp mode. Try to pull any OBDII codes from it. Also try resetting the ECU and going through the Throttle Body open position relearning process (google it).

As a side note, I killed my MAF sensor cleaning it on '03 G35. Had to get a new one. Not good.