I'm having problems getting my Evolution to run for more than 5-10 seconds at max throttle before dying from what seems like lack of fuel. It starts and runs consistently at up to half throttle, but once I throttle up it simply dies regardless of the setting of the high speed needle valve. Yes, I have also tried opening the needle beyond the initial factory setting.
At first this made me think of a fuel tank problem, but I've changed the fuel tank, tubing, and filters without seeing changes in the engine's behavior. Also I've tried two other engines in the plane using the same tank, filter and tubing without having any problems whatsoever, so I'm left with the engine. (I even tried placing the tank on top of the fuselage to ensure that the tank level is above the carburetor).
I've complained to my local store where I bought the engine, and they supplied me with different fuels, plugs, and even a spare needle valve assembly. All have been tried with no changes to the engine's behavior. As a final solution the store changed in my first buy and I now have a second Evolution .46 that I tried out for the first time today. Guess what - the engine behaves in exactly the same way.
I'm operating in Oslo, Norway. Temperatures when trying the engines have been around zero degrees Celsius/32 degrees Fahrenheit. I haven't heard of temperature related problems earlier, but maybe others have.
To me, this seems to be related to the engines ability to suck fuel into the carburetor, or the mufflers ability to pressurize the tank. There seems to be a vacuum effect that "pulls" the fuel back into the tank leaving the engine with too little. Why this happens only with the Evolution and no other engine I've tried in this plane I cannot understand!
This has become very frustrating - the Evolution is supposed to be one of the easiest engines to operate and I haven't been bothered to take mine to the airfield once after owning one for several weeks. Any help is extremely appreciated.

Hoping for miracles
Henning