If all of the above parts check out ok then you might try adjusting the steering box sector shaft.
This is the small nut with an allen head screw inside on the top of the box.
With the steering wheel pointed straight (wheels pointed straight ahead) put a wrench on the nut and an allen wrench on the small screw.
When you loosen the nut the allen screw inside will also want to turn which is fine, but make sure you note the position first.
After the nut has been loosened a little bit you will be able to tighen the allen screw.
It is best to tighten the allen screw only 1/4 turn at a time so that you don't bind up the box.
After tightening the allen screw 1/4 turn, then tighten the nut while holding the allen wrench in place so that the allen screw doesn't get tightened any more.
Road test the vehicle and make more adjustments if needed.
If you tighten the allen screw too much your steering wheel will not return to center so you must back off the screw until the steering returns to normal.
With some trial and error I'm sure you will find a spot where the steering feels better!
2005 ZR2 Blazer / Mods- Spectre CAI, Descreened MAF, Shaved Throttle Blade, 31" Goodyear Kevlar MT/R's, Black Rock Rims, MSD Street Fire CDI & Super Conductor Wires, Accel Cap, Rotor & Coil, Flowmaster 30 Series, Gibson Tailpipe, ES Bushings, Goodridge Brake Lines, Power Slot Rotors - 1996 Impala SS / Mods- Too Many To List - 1988 S10 Blazer / Mods- Too Many To List - 2001 S10 Crew Cab 4x4 / Mods- Too Many To List *Wrecked 12/06*