RE: Why is my motor shutting down with a full charge?
Your problem is exactly the same as the one earlier in this thread. It's your battery. You're trying to draw more Amps from the battery than it can produce. The voltage is dropping, and the low-voltage cutoff is kicking in.
Luckily, yours will improve with use. After a few cycles, that NiMH battery will start working better.
You can improve things by switching to a 9x7 propeller. This will reduce the load on the motor so it won't draw as many Amps. You can switch back to the 10x8 prop after 3-4 flights, but keep your full throttle flying to a minimum.
Above all, don't sit there running the motor at full throttle on the ground for extended periods. The forward motion of the plane through the air causes cooling air to flow over the motor. Prop blast does very little to cool the motor, because most of the prop blast is toward the outer edges of the prop. Extended static runs will cause the motor to overheat in many cases. Best not to chance it.
Those 700mAh-ish AAA NiMH cells max out at around 7 Amps. The EPS300C drive in your E-Starter normally draws a little more than 7 Amps on 7 cells. Even properly broken in, you're pushing the battery pack to its limits.