Help! Transmission problem

[spyder]

I have an 06 quadcab 4wd ram with hemi. It just started this. We live off a road that is straight, 45mph limit and is a series of long steep hills. Normally as I crest one it goes into 5th and 4cyls then when about halfway up the next it will go to 8 cyls and then shift back to 4th. Now in seems to hang in 4cyls and starts bucking like the trans is slipping. I checked fluid and its full and red. Doesn't do it in tow mode and in nor.all mode I feel no slipping in any other gear even under hard acceleration. Please help

 

[SFD213]

Bump.

I have an 04 Quad 2500 Hemi and i feel the same at 60 mph cruise control on and in OD. Doesnt shift up (clearly) or down.