Did you do the work yourself?
The reason I am asking is I have read a few people have noticed elongated holes for the Rack-n-Pinion making the truck behave erratically, as the rack is shifted around when being knocked out of position by hitting bumps or pot holes.
Changing Control arms, unless really twisted or cracked would not change a lot. Maybe if the Bushings are bad, but they can be replaced.
If you are not hearing any clunks, bushings should be fairly decent although they may not be as stiff as they used to.
I just did a full front end refresh with cheapo parts and the truck runs great, so I don't know what you are missing, but you are definitely missing something. Did you do both lower and upper Ball joints (uppers come with the control arm and bushings), Stabilizer bar links/bushing, Tie Rods outer/inner, Lower control Arm bushings. This is pretty much everything between your hands and the wheels.
Did you get your Torsion bars checked? They do wear out... depending on what the previous owner did with the truck they could be worn out and would not support the vehicle adequately anymore, and this would yield some really bad handling.
Hope these few ideas will help.