I believe with some pedals there's a calibration you can do, which involves a combination of turning the car on and off while depressing and releasing the gas pedal - might be worth googling this and giving it a try if it's relevant to your car*
I'm not sure what the issue is, possibly some sort of bad readout with the sensors reading differently to each other but then you'd expect the car to go into limp mode and throw an error. If I were you I'd take it to Nissan, while it seems safe that the gas is reducing in sensitivity (rather than the opposite which would be dangerous) the error system isn't working as it's supposed to and it needs a proper looking at really
edit: *You describe it as a pedal problem but iIt could also be that the engine is lagging? giving more gas and the engine racing but not increasing in speed very quickly may be a brake caliper that is sticking (are your wheels hot after driving?) or a worn clutch issue... but giving more gas and the revs not increasing could be air/fuel starvation or inadequate spark/misfire on a cylinder.