Never had a Pathfinder, but i've had 2 Nissan Frontiers (An 06 and my current '12 - very similar vehicle, although the Pathfinder has IRS). The VQ40 likes revving and likes burning fuel. If it's an 07, has the radiator ever been replaced? You'll want to look into it/the history of these vehicles. Basically the radiator doubles as a transmission cooler and it'll develop a leak. The transmission fluid turns into a "milkshake".
