Like they all stated the 11x6 is too big of a prop, try a 10x6 or evena 10x5.  If your Extra is designed for slow flight a 11x4 prop mightwork Ok for you.
In looking at your pics, it looks ok, except the remote needle valveshould be lower and inline with the carb. When you look at the factorysetup, you will see the remote needle valve inline with the carb andmounted to the top two screws of the rear crankcase cover.

now it is possible the fuel line inside the fuel tank has a problem.But if the engine is running Ok until you point the nose up, then youhave a fuel draw problem. The first thing then is to go to a smallerprop and get the RPMs up so the fuel draw is improved. Then check themuffler vent fitting for the fuel tank, it may be partially obstructedor blocked off.