RE: throtle cuts off on superstar ep
Have you charged the battery? It sounds to me like the ESC is functioning perfectly, and you're hitting the low-voltage cutoff. This can be caused by weak/bad batteries, uncharged/undercharged batteries, or too small of a battery. Since you're using the stock setup, only the first two would be issues.
ESCs generally work, or don't. They don't normally malfunction, especially in the manner you describe.