My 2005 QX56 drives just fine, but... when on the freeway going 70-80 it will shift into overdrive but anything(even a stiff breeze) will cause it to immediately shift out of overdrive. Then it will shift back in and repeat over and over.
transmission shot?
can you give any more info?
did you just buy it?
mileage?
any maintenance done on it recently?
any error codes?
any modifications done to the engine?
does it happen on hills? at a certain RPM? can you repeat it? what happens if you manually shift into a gear, does it stay in gear?