From what you describe, it seems to me that the problem is lack of elevator authority in the landing phase since a aft CG would be very apparent in normal flight. In the real airplane the CG moves forward when the gear is deployed and this would also agravate the lack od elevator. Another factor is that the flaps blank airflow over the elevator. I used to have a problem during flare with flaps down until I start using full rate on the elevators as soon as I set up the landing. HOpefully this will help.
JG
http://mywebpage.netscape.com/warbirdscale/