Thanks Dan,
I somehow missed the changing left bar links on aircraft proving ground. The aircraft supercalculator I was after. I used to have a copy on my old computer, and now am glad to have it again.

@ all:

If the CG is too much aft, the nose of the (trimmed) plane will come up when speed decreases. Power application with properly aligned engine will initially just accelerate the plane. Incidence will enter the picture only after the plane speed changes.
If the OP's plane reacts violently by pitching up by power application, the engine thrust line is too much up! He wrote that the plane behaves well the moment throttle is reduced, so COG and incidence must be very close to OK.