Ok so I am asking this question for someone else so I really don't know a lot about the truck. what I was told is the transmission will work fine shifting through gears and everything until it has been driven a ways and it gets warmed up. then it begins to upshift and downshift. They said it has the electronic shift transmission in it of some sort. I am not really sure what trans is in it but anyone with a similar problem or suggestions on how to fix this. also they said they have changed the trans fluid and filter and was told it could possibly be a sensor on the trans and they hd changed the speed sensor on it. thanks