Onan generator dies like its out of fuel then runs fine?

I'm not very techy and know diddly squat about mechanical things, but I recall when we gave ours a huge service at home, filters, fluids etc, I think I read somewhere in the manual that you have a setting on it for different elevations you should change. Just mentioning and might be worth checking in your manual for operating at high elevations versus sea level etc.

?Carburator adjustment at high altitudes?????? Just mentioning FWIW.