I bought the truck a couple of months ago to drive to our gun club. Wife kicked me out of the Xterra. I get really good gas mileage with the 4 cyl and 5 spd. There is one issue that I don't like though. When shifting gears it takes a long time, 2-3 sec., for the rpm to drop when I push the clutch in to change gears. Is this part of the emissions package or is it something I can fix?