adam_jorgensen, on your update post #16 you said "So I tightened it and no more air comes out. I get a good seal now. So hopefully my bubbles will stop now",well did they? If you have a fuel flow problem, which bubbles in the fuel line is, then a new engine won't solve the problem. You'll just have the same problem with a new engine.

Part of the problem may be the vibration you are experiencing as this will cause bubbles, so if you are running a damaged prop toss it and get a new one. If not, at least make sure it's balanced.

Another question that hasn't been asked is, how is your compression? While 30 flights isn't much time, even the best engine won't last long if it's been forced to ingest dirt due to poor "landings" or crashes due to constant deadsticks. I've had worn engines that would run and idle fine when first started, but as they would warm up and the parts of the engine would expand they would lose compression and would only run in the upper RPM range.

Good luck, keep trying, keep it clean and leave the drill motor and bits in the tool box