My 2003 Infiniti G35 is tuned with a FBO last week it started this weird thing where it will start stalling and idling horribly and stalling but didn’t die then I left it for a day it worked like it fixed itself yesterday I was driving and all of a sudden it stalls out and idles horrible and won’t let me rev past 1k rpm and then if I tried to it will die out so I thought it leaking air from somewhere so today I got a new maf sensor and connector because the old connector got burnt up because I had a oil leak and it kept steaming up and cause it to burn so I got a new one and the code it threw for that connector went away then the codes that are on now is the p0113 - P0031 - P0051 I will try cleaning the throttle body tommorow but my throttle body is very new because I just got it in November before my tune but I have a long tube intake and my fender liner broke off sometime ago and I have been too busy to replace it so I think it gathered a lot of dirt because of that so I will try cleaning that tommorow and see if the problem stops I know all the 02 sensors are bad which is why it threw the other codes so that can be it too but I don’t think that will make the car idle out and act the way it is and not let me rev past 1k rpm and stall out but I might be wrong anyone have suggestions or have had this issue before and know how to fix it

 

Clear the codes, you say you have a new MAF sensor but you're throwing the IAT/MAF code still which is PROBABLY the main issue.