My truck pulls to the right whenever I take my foot off the gas pedal . What can cause this ?

You may want to check your brakes (right side front and rear). If it's fine w/ on the throttle (and fine while braking??) it's likely something (probably small) is stuck b/w the caliper and the disk/rotor. On the throttle, there is enough speed to overcome it, but while coasting it's making a difference and causing the right wheel (whichever one) to turn slower than the rear. If your Pathfinder has rear drum brakes it's most likely the front. For what it's worth, my '01 Frontier had the right front inner fender (rubber piece w/ plastic pushpins) come off and some got caught in the wheel/right front brake b/c it would pull to the right while coasting and on the throttle.

Check your tire air pressures. After a drive, touch each wheel to see if a brake is dragging. A hot wheel will point to the problem. It may also be a bad hub bearing.