Originally Posted by sc32valve
Sounds like lack of forced induction at elevation
Plus a lack of information.
Which mountain? What kind of grade? What roads?
How heavy is the trailer/raft, and what else might be loading the vehicle down.
I've seem some rather heavily laden V6's scoot up I-70 right along with normal traffic. Don't know if they have engaged sport mode for more oomph and higher shift rpm or not. They don't appear to be overly taxed by the altitude even on Loveland at nearly 12K.
There are other paved 2 lanes that are much steeper.