Fix the fuel by putting 8-10 drops of Armorall(tm) plastic protectant. Its available at most auto dealers, auto parts stores, and discount department stores. It contains a defoamer that will kill the bubbles dead. You can shake a jug of de-foamed fuel as hard as you want and it will stay clear.
Symptoms of foaming fuel:
The motor won't track the needle valve and richen up smoothly on the ground.
The motor runs rich for a moment, then leans out by itself, then goes rich again.
The setting changes drastically when the plane is launched. Typically, it goes dead rich because the fuel was foaming while the plane was being held, but the vibration changes and it quits foaming after the launch.