anyone have this problem? 2005 F250 6.0 auto. once in awhile while driving down the road the trans feels like it slips for just a half second. sorta like a manual if you barely press the clutch til it starts to slip and then let off. It doesn't do it every time and I am beginning to wonder if it is when it thinks it needs to down shift out of overdrive. i have noticed it happens more often if i am going up a hill and the truck is lugging down a little. after it 'slips' it is back to normal for the rest of the trip. any suggestions would help. the truck is stock with 108k miles. fluid look good, no leaks.