It's too lean. Fuel supply is fine until you open the carb all the way, then it runs out of fuel and dies or acts lean (RPM's drop)


Close throttle to idle
Run the high speed needle all the way in
Now back the high speed needle out exactly 5 complete turns

Set throttle to 3 clicks above idle and start it.
Go to full throttle
While it is running at full throttle, lean the high speed needle until peak RPM (use a tach)
When it stops gaining RPM, quit leaning the high speed needle and back it up about 1/4 turn rich

Now adjust your idle the same way.
Turn it off
Close the throttle
Run the idle screw all the way in until it stops
Now back it out 3 turns

Start it
Idle speed
LEAVE THE GLOW IGNIGHTER ATTACHED
Lean the idle screw and observe the engine. It will gain RPM's as you lean the low speed needle. Just like the high speed needle picks up RPM as you lean it
Don't bother to transition it yet
Just keep leaning the low speed needle and observe how the engine picks up RPM
Eventually you will lean it too far and it will start to slow down
STOP
Richen it about 1/8th turn
Take the glow ignighter off and see if it stays running. It should drop RPM just a little bit but it should stay running

Now go back and double-check the high speed needle
Full throttle
RICHEN about 1/4 turn
Now lean to peak (use a tach)
When you find peak RPM, richen it up about 1/4 turn

Go fly it.