Driving Straight?

I searched a little on this so if it's a repeat, I appologize. I'm having an issue with my Stang not wanting to return to center. It's not very predictable and just irritating. I've replaced ball joints, struts and checked everything for play. It's tight. I've also had the front end recently lined up. It also kinda "self feeds" when turning (hard to explain, I turn and its like the power steering pushes the wheel on over in the same direction and I have to pull back to keep it from going too far). Anyhow, it won't run straight down the road. If I let go of the wheel, it will stray off to either side (usually the side I just corrected from; like if I make a right turn it wants to stray right) so I'm constantly fighting it down the interstate. I was told today that it may be a leaky spool valve in my rack. It's the only thing I haven't replaced. I have 128 thousand miles. Anybody had this trouble?
 
I believe the stock system does not allow for caster adjsutmetn, or minimal at that. Maybe some C&C plates?

You shoudl ahve a sheet with the actual readings from the alignment.

Chris
 
I had the sheet but of course, I lost it. I'm gonna have them give it a second shot after I replace the rack. I did notice that the factory rivets have been drilled and the camber adjustment is all the way over to one side on the driver's side. Maybe I should grab some caster/camber plates before I go for the alignment. I think the car may have been in a bump and grind at one time anyhow. Maybe the strut towers aren't right.
 
If you ever plan on lowering the C&C's will be in yoru advantage.

And at that you can get FMS springs for under $150... so for $350 if youc struts and shocks are in good shape you are lowered and ready to be aligned...