Hi,
as MSFS is a free for all game cathegory simulator, anyone can do any modificatin to it . Thats why if you use the out of the box planes, you have a great chance that those will give you a bad time when you try to fly them manually IFR.
1rst of all get a descent 3rd party flight dynamic, if you want props then go to:
http://www.fsd-international.com/flight_dynamics/ If you want jets:
http://people.zeelandnet.nl/johd/FDE/fde.html Note that those are only dynamics, and they are the best available within the simulator limits. Also they should be linked to specific visual models or if you do not carr about eye candy then just link them to any default airplane. As long as you do not look from spot plane or replay, you should be ok.
Cheers