I have a 2001 Nissan Xterra that I have replaced the ball joints, tie rod ends, and upper control arms. I had it aligned, and after about 500 mile you can start to feel that it has worked its way out because it starts to feel like it is 4 wheel drive when you turn the wheels sharply like backing out of a parking lot. It is wearing the front tires on the outer edges. Does anyone have any idea what could cause this? One more thing is all parts were replaced using MOOG.

starts to feel like its in 4 wheel drive? can you explain a bit more on that? Are you saying it feels that way when backing out of a parking lot, or that when you are driving forward at speed, or slowly.

Do you notice anything when driving straight, on a good road surface, either at speeds or slow?

are you only feeling it when turning in forward, and again, at speeds, or slowly ?

try and shed a little more light on it, help will come along easier that way..

When you cut the wheels at low speeds it feels like the tires grab the road and it will jerk it does this going forward or backwards either one. It feels like say you are on snow and turn onto a dry road in 4 wheel drive the way it jerks. At interstate speeds of 70 and 80 mph you can let go of the steering wheel and it will stay straight.

have you confirmed that it is NOT stuck in 4wd? dont assume that because the indicator light isnt on, or that the 4WD shifter is not in it means its out of 4. take it to a spot with lower traction, snow covered, grassy or muddy area and feel it out, forward and reverse to make sure the front wheels arent pulling. that is something you would want to confirm A.S.A.P.
sounds strange that it would work out far enough to cause that kind of action without feeling it want to pull to either side at higher speeds.

also, who replaced the parts, and did the alignment? Should it not be a 4WD problem I would have taken it back to the place that did the work if it started after only 500 miles after work was done.

It's not stuck in 4wd. I've been driving in 6 inches of snow the last couple days, and have had it in and out of 4wd several times. I've taken it to have it re aligned 3 times since August, and the shop couldn't find anything. Monday I took it to a different shop for a 4th alignment, and that shop couldn't find anything other than the camber being off either ether.