It's likely that your high speed needle was set too lean, which is likely why you lost power when you went to full throttle. Did you ever go to full throttle on the ground while holding the plane securely and making sure it ran right there?

The advice above about the engine starting backwards is right on.

Fwiw, Enya engines are, in general, very high quality. The starting backwards thing is a trait of new engines with high compression, a good thing.

If I had to bet, I think it's likely you will have a simular experience with an OS engine as you have had with the Enya. I think your problems come entirely from not setting the engine correctly. If you want to spend money on another engine, take a look at the Evolution engine. It has limiters on the mixture settings and good documentation that can reduce your problems until you learn more about proper engine care and feeding.

I know it's hard, but you should also be patient and try not to charge ahead on your own. It's most likely to result in broken gear than anything.