Misfire/lean at high altitude

[catalina34]

I am getting a lean bank 1/misfire code when I drive to the same mountain town. It throws the code at nearly the same place each time. Otherwise I never get the code. In advance, the MAF is clean and the fuel filter is relatively new.

 

[Granite]

Seems to me you have unmetered leaks or vacuum leaks which are so slight they only show up where the air thins out.