TJ not returning to center after turn

I have a 1997 TJ Sport with power steering. I posted this question a
while ago but never really got an answer. The problem is that the
steering wheel does not *completely* return to center after a turn. It
attempts to, but never completely bounces back. Also, when driving
straight down the road, the steering wheel does not "bounce back" to
center if it is turned or flicked a little bit. It's kind've like
something is binding. I asked a mechanic and he suggested checking the
U-Joints, which I did and they are both OK. I suggested an alignment
due to a bad castor angler but he said the castor cannot go off
enought to do what it's doing. The dealer I called also said an
alignment wouldn't fix the problem, and it was probably a worn out
part. Here's what I know:

Recent new Steering Box (problem happened before and after
replacement)
Good Front U-Joints (not binding up anyways)
New sway bars (don't think that's related but I'll put it up here
anyways)
Recent lube of all zerk fittings when I did my oil change a few months
ago.

I haven't had it aligned since I bought it, however I have put a 2
inch spacer coil lift on it and when I did that I did a self-
adjustment of the toe-in and the steering wheel centering.