2002 Xterra Overheating after a lot of work

Good afternoon all,

I currently live in AZ and during the summer, my xterra overheats quite often. Last summer I replaced the water pump, radiator, fan clutch, temperature sender, and a miscellaneous engine part. I have also made sure it has the correct amount of coolant in it, yet it still overheats on hot days. Before I did the replacements, it was overheating while driving no matter the temperature, after the upgrades, it only overheats when the temperature reaches a bit over 100 and I have to travel over any type of mountain. My dilemma is that I have to leave the valley and therefore go over the surrounding mountains mid summer. Is there anything that I could do to limit or eliminate the overheating issue at this point or is it just something I should expect with a vehicle of that age.