Could be several things from a vacuum leak to a faulty MAF or a precat O2 sensor. Try to push the X in high RPM and see if there is any hesitation. Also Does it show any erratic idle rpm behavior? If the truck works fine and you get good mileage it may be a temporary glitch. In that case I would suggest to clear the code and see if it comes back after some time. Otherwise the dealer will be able to tell you what the issue is for few hundred $ for the diagnostic and more to fix the issue. Before going to the dealer you can try to clean the MAF. That is very easy.