FL Columbia w/Detroit Diesel+10 speed-piece of junk!!!

I drive a 2009 FL Columbia with a 10sp and that has to be THE worst engine/tranny combination every "designed" to work together!
It's not bad enough that it absolutely "dies" at the mere sight of a mountain or hill with more than about 18k in the wagon, but every time I try entering a freeway and winding up and out to merge, the piece of crap gets to 57mph and then just "drops"! It feels like the engine just shuts down for a few seconds! Although only for a few seconds, it takes what seems to be a minute or more to gradually, slowly, build back up the momentum you were building up originally to get you up to speed. I've driven a lot of different makes and engine/tranny combinations over the yrs, but have never experienced anything even close to this. I've reported it to the shop and they tell me thats normal for a detroit engine. If this is normal, I'll never drive another one if I can help it, and I dang sure would never purchase one!
Another "nail in the coffin" I forgot to mention, when using the cruise control, this piece of junk seldom remains at the set speed-even on flat ground. Instead, even though the truck is goverend at 63 and I set the cruise at 63, it likes to rev itself up to 68-70 mph and then drop back to about 57-58, only to ease back up once again. An it always seems to do it at the most inopportune times, like coming into a 60mph zone or something. Thats when it will inevitably rev up to 68-70! Its done it more than once! WTF is up with this piece of crap?