The occasional "flame-out" is fairly common with a new, tight LC4. Break-in can take a few thousand miles.
You didn't mention what your idle speed is... if its around 1400-1500 rpm, it's a bit too low.
Try raising your hot idle speed to 1600-1700 rpm... too low an idle speed will tend to exacerbate the problem.
When the idle speed is set correctly, the low speed mixture screw will become a bit more "responsive" to adjustments.
At your elevation, the idle mixture screw should be set at around 1.5 to 2.5 turns out from seated.
So... how's tricks?