You didn't mention which engine it has. Or if any fault codes were pulled out of it. If the fluid is clean (not burned up) and the filter is fresh (not plugged up), I'd take a closer look at the MLP sensor (Manual Lever Posistion Sensor). This is a pretty common failure point on these vehicles.
I'm not of course saying to just go out and replace it without the proper diagnosis. But hopefully this will steer you in the right direction!
If you do end up replacing it, I'd suggest getting one from the dealer, not the aftermarket.