Shaver Lake, California? At altitude, you loose 4% horsepower per 1000ft above sea level.
Not my words but I agree with the info. I 'hijacked' this info off another site. Hope this helps.
"It's a common problem with big changes in altitude. There is an idle stop
adjustment screw on the throttle linkage right at the carb. You'll need to
turn that screw in a bit to raise the idle stop of the carb. This is
essentially the same thing as keeping a tad bit of throttle applied at idle.
This will at least allow the engine to idle at high elevations. But you
will still experience a significant drop in power, which will likely need to
be compensated for by a drop in pitch of your propeller. Also, if you
intend to run at that altitude for an extended period of time, the carb
should be re-jetted for that altitude."
95 Max 2300SC
Nine Mile Falls, Washington
"If you look like your passport photo, you probably need the trip"