The 2002 Nissan Xterra (4WD), automatic transmission, I drive for work is starting to have trouble traveling up hills. Just the other day I was traveling on a freeway up a fairly steep grade for ~6 miles. It wouldn’t down shift and the pedal was to the floor while I watched the speed slowly drop. I started noticing earlier this year that it will disengage the cruise control on this same steep grade, though not every time. This used to be my personal vehicle and I have been driving it since 2002, so I know how it drives. A mechanic test drove it today and chalked it up to age (our admin assistant took it to the mechanic, so I didn’t get to talk to him). Its got something like 170k miles. That is a lot of miles and it is 10 years old, but I am really wary of any diagnosis based solely on age.