suspension

Have you checked the fluid in it since it started to do whatever it does?

Do you know what caster is? If not i will inform ya. You know how on a bike the forks are at an angle, so the wheel wants to stay straight? The angle of the fork is basically caster. A car will usually only have a couple of degrees, not as extreme as a bike. An imaginary line between an upper and lower ball joint would show caster......

-Josh

Caster is a VERY VERY good thing for the mustang. With the stock alignment, you actaully gain positive camber in suspension compression. This is bad when you are trying to make a hard corner. If you add enough caster (think 8*!!!) then you can actaully start gaining negative camber. It isn't enough to cancel the camber loss from body roll but it is certainly better than gaining positive camber. With CC plates, you will normally be able to get +3* of caster which is fine for a street driver. When you run tons of caster, you also tend to overstress certain front suspension ports (but I don't remember what now ).
On the power steering thing, does it feel like the rack locks up at times? That can be cause by insufficient fluid pressure and flow. It may be possible with the stock SVO pump and SN95 rack. I know it can happen when the quick ratio GT rack is used with the stock 4cyl pump, but only when using the steering a LOT, like an auto-X.
If it just feels like it takes more force than it used to, then that is probably normal. The SN95 rack I beleive has less overall effort than your stocker. If you actaully WANT LESS steering feel, I suppose you could replace the pressure valve on your pump to make more pressure, but generally, steering feel is a good thing.
Sounds like a nice setup to me.

I have never heard of cross caster!!!whats that????? Was he B.S.ing you? I know alot of alignment shops just like to set the toe and collect the dough. Make sure they check everything when you get it done!!!

I did a search on google and cross caster/camber is what they call the "method" of adjusting alignment to compensate for road crown. The car will always drift to the side that has the least negative camber, so they would set the right side camber a little more positive (less negative...depending on spec) than the left. So I guess he was trying to tell you that the caster is already set as positive as it can go, so he cannot adjust the FR wheel any further??? At any rate on a flat road it should not drift, but on a crowned road it will drift downhill. I suppose you could have him set the FL wheel with a little less postive (more negative) caster to get the same effect. The only thing is that drivability/handling might take it in the pants like Bhuff said....

The stupid cross caster thing was driving me crazy. I looked it up, and it is simply the difference between the caster on each side. http://autorepair.about.com/library/glossary/bldef-086b.htm
Caster isn't adjustable from the factory. My 88 ford service manual shows the caster spec for a 2.3 is between -.85* and +.65*. Based on that, it is possible to have up to 1.5* of cross caster from the factory.
I wouldn't be worried.