As previously mentioned, it's probably the trac bar. I was stumped as to why I had to readjust the steering wheel after wheeling sometimes until I had the steering wheel require re-centering after doing NOTHING. I found the trac bar cracked in the arch. Get a forged trac bar.

 

I went with jks front and rear track bar and synergy tie rod and drag link. I've never had to make an adjustment in 5 years of heavy wheeling and it dramatically improved the ride from stock. I would highly recommend something aftermarket in those categories including the grade 8 bolt kit.