The one thing that I have noticed is you have not checked the balance of the prop you are using. This can cause the bubbles you are having. I can also be a leaking fuel valve too. Here is a couple of things to try. Make sure your prop is well balanced or the vibration will cause the fuel to foam in the fuel tank. Another thing is to exchange the fuel valve for just straight line and see it the engine runs correctly. Cut a small piece of medium fuel tubing about a 1/8 long and slide it on the the needle valve before screwing it in. This will help seal the needle valve in case it is leaking air in.

When you switch to a fuel dot you need to run a third line from the tank for fueling. This way you will not flood the engine when fueling. Set this third line up with a line and clunk. The other two lines still hook up the same. Good Luck.