Front Suspension problems of the 2005 Nissan Xterra

2005 Nissan Xterra purchased in 2006 with 19,000 miles current mileage 59,000. After the purchase I noticed that when the truck hits ruts on the highway it will follow them. At times the truck feels completely uncontrollable. About two weeks ago the truck caught ruts that threw me into the other lane no amount of correction could stop it. Had there been a car next to me there would have been an accident. When I asked the dealer to investigate my safety concerns they wanted to charge me money rather than address my safety concerns. My research in 2006 showed a lot of complaints on Xterra web sites about steering issues but the owners wrote them off as being the nature of the beast 4wd. VIN available on request I do not have with me. I have owned a 2000 Ford f250 4x4 and two 4x4 Ford rangers 02 and 04, none of them ever caught the ruts in the road. None of my other current vehicles have rut problems either with twice the mileage, 90 Geo 152,000, 92 stealth tt 150,000 and a 67 skylark 96,000, all have original front end parts.