Not sure what is wrong with my 1997 Nissan Pathfinder 4x4 auto transmission it's started to not sift in high gears no code but one and it's p0734 4 gear ratio is improper but it revs up it seems to shift to 3rd on down hill but on any grade or a pull it will only go 40 mph change fluid and filter made sure the lines to the cooler wasn't clog no metal chunks on the magnet just normal wear and tear any help be really appreciated