I was messing around loading aircraft parameters for my Valkyret into FSEdit and checking the balance with the box drawing in AirWrench.  The Mean Aerodynamic Chord would not resize when I changed the size of the wings, and the aircraft would not fly.  Then I borrowed the AirFile from various aircraft, but loaded my own CFG.   I actually got the aircraft flying well that evening, with small variations depending on which AirFile it flew with.  But – there is something strange happening at high speed???  I was aiming for Mach 3 or so.  Once the aircraft attains about Mach 3.2, the fuel flow increases right off the clock.  I could actually seen the indicator needle moving.  At the same time, the thrust went wild, the aircraft accelerated like crazy, but seems to hit a brick wall at Mach 4.6, and will not go faster, even in a dive.  While this is happening the thrust leaver can be pulled right back to idle with no effect, showing no thrust decrease and not slowing down the aircraft???  Is this a glitch in the simulator? Or the AirFile, Or what?  Anyone seen this before?  If I limit the thrust manually to maintain below Mach 3, then everything seems fine, but if I release the aircraft, you know most people will just fly it like a boat, balls to the wall, and that will not work!