cedthered

Hi there, the Saito pulled the Piper around very nicely! The plane flies well, albeit a little heavy, so she does fly scale.
But, I have a problem, the motor runs very nicely on the ground, and during taxi, it idles like I have never seen a rc motor idle, slow and beautifully, it revs out very responsively, and it really screams at full throttle, but as soon as she gets up in to the air and flies for a while, the motor dies when I open the throttle fully. It does give me a fair bit of warning, and I run it with permanent glow at the moment, as the motor is set rich, as I am running her in so i just back off on the throttle and fly her on half throttle.
I have a Keleo ring on the motor, the motor is out in the open, so it does not get too hot, and it fires on all cylinders when she does run, and dies on all cylinders when she dies, so it cannot be glow plugs, and I cannot see any leaks in the fuel system. I am running the motor with the big tank I took out from the H9 Sopwith wreck, and not the tiny TWM tank. I do not have a remote fuel filler, and fill her up straight in via the carb line.
I am wide open to suggestions...