bump steer???

ok...what i am looking for is any help on the technical side of bump steer. I am doin a one off lift kit for my armada...check out my profile if u wanna see it...its gonna be a 14" lift and its got a 6" now. It has rack and pinion steering. Even now it has bad bump steer and i wanna cure the problem and i figured someone on here would know the technical solution for bump steer. When i hit a bump and the wheel goes up..it changes the toe in. The tie rod ends have been extended and have heim joints on them now so i know its not that. I was thinkin it has something to do w that angle that the tie rod is out of the rack and pinion? Any help?