RE: engine shutting down on take off
Check your throttle cable to make sure it is secure and can not vibrate. I had a difficult problem exactly as you describe and it was the throttle cable vibrating. That causes the needle valve assembly to go back and forth, moving the needle valve in and out, which (in my case) put bubbles backward into the fuel line. I know that this sounds like a stretch, but it's worth checking out if nothing else is panning out.