There isn't a rubber bumper, the gas pedal is just an electrical switch, two of them actually. There's a linkage arm from the top of the physical pedal that goes to the top of the assembly and it pulls on the switch arm.

You can always verify the APP signal by looking at the throttle% values in an OBD2 scanner.

 

I have same problem if you find out how to fix plz.let me know

 

My 06 g35 has same problem i change my pedal out worked fine for a day and it started up again 2 days later, it sporadic but now it happens even when I am driving and it slipped like it was in neutral and then when back into gear

 

First check your brake fluid level to make sure it's not low, then plug in an OBD2 scanner and see if it pulls codes, if not then take your vehicle to Nissan/Infiniti for a diagnostic. It will cost you 1 hour of labor and they'll tell you what the problem is.