I had a '93 Dodge W250 with a kingpin Dana 60 up front and when I bought it one of the front tires leaned in, the top of the tire was about .25" closer to the body and the bottom was .25" out. This caused some irregular tire wear. The fix is to replace the spring and bushing at the top of knuckle. All the parts are available as part of a kit, which is what I purchased:
http://www.quad4x4.com/qk4512.html While you've got everything apart might as well change the bearing at the bottom as well. I would go that route and see if it fixes your issue.
Wow, just checked the price of that kit and it has really increased since I did the problem. If you want to start the cheaper way I would just replace the spring and bushing. Ultimate Cheap-skate way to fix this would be to open up the spring retainer and put a grade 8 washer on top of the spring. This will increase tension on the bushing and should help straighten out the knuckle. I don't like to use that fix because normally if the spring is weak the bushing is worn as well.
Just went back and re-read the OP's original post. Wow I see you've already tried some of the fixes, and I feel a little silly for re-hashing things you've already tried. Sorry about that.
I'd try putting one a fender washer under each cup on top of the springs and see if that helps a little bit. You could even stack two washers on top of a spring to increase the pressure on the bushing. I really think that your issue lies with the spring not applying enough pressure to the bushing. Did you use good quality springs? Were the parts new? If that still doesn't resolve the issue I would say it's time to change the kingpins. While it is rare they do wear out. Lots of heat is a must on this job. Quad 4x4 also sells a 3/4 drive impact socket with the hex needed to remove a kingpin. That will probably make removing them much easier. I've also seen some make a big allen key and use a 8' cheater pipe.
