01 4.4 Weird shifting stuck sport mode?

[martinibmw]

hey guys, first time poster long time visitor.

I have an 01 x5 4.4 sport with an automatic transmission. Every once in a while it shifts oddly. What I mean by that is it wont shift gears until it hits 4500 rpm then shifts to the next gear. When its doing this, it wont ever shift into 5th gear. I put it in the sport mode and try to force it into 5th but on the display it highlights 5th for a sec but then goes back to forth. On the street I end up only in 3rd and wont go to 4th. This goes on 75% of the time I drive this. Any ideas, I am pretty handy so if you guys have any ideas of what to focus on I would help a whole lot.

Thanks,

Pete