helenp - 9:48 am on Feb 17, 2013 (gmt 0)

It is certainly related to short-phrase key-terms. For example, on my site Key Term has gone from the top of page 1 to page 46, but Key Term Prices is at #1, and Specialised Key Term is at #3. This makes 1, 2, 3 and 5 better candidates than 4 and 6.

I agree with that,
I have same problem.
Highest density words in order
mycity
villas
apartments
Doing bad in mycity villas (in some countries only)
doing ok in mycity villas other words
but doing well in mycity apartments as apartments does not have that density.

And there is no keyword stuffing, those are the key words with most density naturally.