98 Tahoe alignment problems

[sertadormae]

Purchased a 98 Tahoe that had a 2" body lift but had regular passenger tires on it. A couple of months ago new wheels and tires(BFG All terrain k/o's) were added but now it pulls both left and right. I had the frame checked out and found it was 3/4" out of square and had it corrected. What can be or should be done to be able to get the alignment to stay true. I think something might be worn out somewhere but i don't know where to start.