I notice that when I am reducing power and slowing down during approach phase, the airspeed will drop like a rock from 120 to 70.  It doesn't matter how slow I reduce the throttle.  It's also very touchy on final and very difficult to get an accurate 500 fpm descent rate, the plane can be too high one second, then too low the next and even too slow or too fast.  It doesn't seem to matter if I have full flaps or a full load.    Any hints?

Do you have the optional (more realistic) FDE or the one that came with the package?

The one that came with the package.  I tried the optional one, but P3D blew it's cookies on the gauge file.  

 

I just saw a thread on prop pitch.  I have not been trying to adjust the pitch as still trying to get yoke setup yet again, maybe there's something with that?

Maybe. I would just assume it's stuck at full forward, and therefore delivering as much power as possible. But perhaps something is changing it. Maybe it's just normal turbine lag? That's a pretty tricky thing to get a handle on if you aren't prepared.