Your post confirms my suspicions and findings. I have only made one flight so far with the Webra (9x4) APC prop and 12% nitro, glow plug ??? I have no clue what it is, something I pulled out of my used plug box. I took off slightly rich and it ran good for about 2 minutes or so and then started sagging. I wouldnt say that it was ever truly "on" the pipe but it might have been. My needle only needs to turn a small amount to go from too rich to run to too lean, ( maybe 1/2 to 3/4 turn).

What is the best plug and fuel for this engine ?