Spring adjustment/sag YZ250

Here is what I have:

1. I measured the Installed spring length with wheel off the ground and it is exactly 10" with the adjuster nut slightly below the halfway point of available threads.

2. Measured from axle to a point on fender with rear wheel off the ground. Call this (a).

3. Let the bike down slowly till it's under its own weight.
I re-measure. call this (b).

4. The difference between a and b is 3 3/4"
Now I sit on the bike and a friend measures the two points again. call this (c)

5. The difference between b and c is 2 1/4"

This felt pretty good but seemed a little soft and the rear tire would seem to mush some in the whoops. So everyone is telling me to re-adjust the sag. Static being about 1" and Race about 3-4". I consult the manual. The book says the installed standard spring length should be 9 5/8" So I tighten down the adjuster on the spring so it measures that length. The adjuster is almost all the way to the bottom of the threads. (when I notice most other peoples spring adjusters somewhere about halfway in the threads.) Now I get these measurements:

Between a and b is now 1 1/2"
Between b and c is 3 1/4"

Took it for a ride and it felt a lot harder and firmer. But now the rear wheel keeps swapping in the whoops and feels loose and unstable. (I know I was running 18psi in the tires over gravel at the time and if I lowered pressure it would have helped some in the slippery department but not that much.) but just adjusting the spring to rec. specs made this thing from sluggish to a bronco.

All you tuning pros please make your recommendations on spring length adjustments or comp/rebound adjustments to tame the rear end yet keep to near recommended sag.

I am 6'00" 165lbs B rider mostly enduro with sporadic track work. Or to put it another way, tight-n-gnarly with no big triples.

Well, I left my spring adjustment at 9 5/8" because this made the static and race sag fall into the required range. I turned in my clicker all the way and came back out 10 clicks. This seemed to help a lot. Maybe fine tune a little more a click or two in either direction from where I'm at and see how it handles. But I think is is closer now than how the shock was originally set. When you get used to riding something that is all out of whack, it's hard to know what it should be like or handle like...untill you ride someone elses who's is set up properly. So,I'm feeling fairly content with the new setting and I now have to readjust my fork settings because they seem to be out of sinc. with the new rear setup.