Sorry I took so long to reply, I have been busy, lots of places to visit today.
So, what did I change, short answer nothing! ...Long answer, I imported the fbx file you sent me into 3dsmax, all of your pivot points for the control surfaces were correct (world aligned) but the pivots for the engine and spinner appeared incorrect, Y axis was aligned to Z axis, (see pic) so I changed the engine and spinner pivot alignment and imported the new fbx file into RF, the throttle delay had now gone. So, I went back to 3dsmax, reversed the changes I had made and changed only one at a time (engine and spinner) to see which one was causing the problem, answer none of them.
All I can say is it must have been a corrupt import session that you initially had, from Blender tthanko RF.