Quick run down, we drove my truck to drop me off at work 50 miles one way. It did fine all the way there. Pulled in and put it in park. Never shut it off. Gf dropped me off, made it a mile away when it kicked out of drive. She pulled over and put it in park, and then back in drive. It began to move and then when it shifted to third it kicked out of drive. She said it will move all the way over on 1 and has reverse. Its just when it is put in drive and on any type of incline like an interstate ramp is when it has the most issues. The tow truck driver said it kicked out of gear on him when he drove it up on the flatbed. It did fine on the second attempt. It acts like it's out of fluid or something, but it's full. The truck has 95k on it. Any Ideas?

 

Check shift linkage. It may be just slightly off where it does not lock into detent ball.