I just remembered last year I was having problems with my engine cutting out and it turned out to be the old syringe I was using to fill the tank, the black rubber piston had deteriorated from fuel and that black crap was blocking my filter. It was running OK on the ground but as soon as I got into the air, it would shutdown.

I do agree with jaka, use an OS #8 glow plug. On the expensive side, but it is the right choice for that engine.

Other things to check, is your clunk free to move inside the tank, also are all bolts on the engine tight so that you don't have a pressure leak?