Neil, I reckon the problem lies in holding the joystick BEFORE the Chateau Mouton breathes properly - the nose just can't find the right direction- or at least that was my observation on that flight.
As an Evinrude owner, I'll do my best to help you down!
though I thought you had that sorted with SX 181 ( let's let this one fly at 51000').
I think you need more time on the flight stimulator ( not a typo).
Ps if you're using the google earth one, you're doing bloody well to land any plane. The guy in the Citation must have practiced on it, and thought he had it sorted......but forgot about real life.