I don't know what is going on with your YS, but you really ought to wait and talk to Dave or someone that really knows their YS engines. I could tell you how to break it in too, but that won't help you with your problem.

I would not run it again until you know more...Make sure you're using a fuel filter and clean out the regulator. If your tank has the smallest leak in the world, it will completely kill the performance of the engine and kill the engine in the process! Checking the tank won't do it, most of the time you have to replace it to know if that was the problem. Not getting to full throttle sounds exactly like a pressure problem. Get new lines and a new tank...MAKE IT TIGHT!

Do not fly if you're not COMPLETELY satisfied with how the engine is running. Talk about a way to ruin your day! Nothing is worse than a bad running engine, especially one that dies when you're trying to learn this stuff.

Keep us updated on the engine...

I also wanted to say, don't expect this hovering thing to come quick. It takes most people a good year to really get to the point to want to get to. Take your time, don't rush ANYTHING, and enjoy every minute of it.