When an airplane is in a vertical attitude, the fuel system is what can give a lot of trouble.  Fuel draw will be diminished because the engine must pull fuel straight up from the fuel tank.  If the engine is running at reduced throttle, then fuel draw is also lowered because the engine will have less vacuum to draw fuel.  If the airplane is so light that a very low throttle setting is used to hold a vertical line, then you may need to use crankcase pressure with a fuel regulator to insure good fuel supply to the engine.  With just muffler pressure to the fuel tank, it would not be abnormal for an engine to quit after a bit of running with the airplane in a vertical attitude.

The brand of fuel would not be the cause of your engine's quitting.

The setting procedure detailed in the O.S. manual is a good one.  You can also hold the airplane vertical and adjust the high-speed needle so that the engine is a bit rich of peak RPM when running at full throttle.  Adjust the idle on the ground for good idle RPM and good throttle transition.  After that, there's little else to do.