Well recently I have been having issues becuase of the wind. It's caused me to worry alittle when I almost drift into another lane. I also remember it being worse when I used to run a hardtop. Now I have a halftop so less wind resistance but still an issue. It has been windy recently but if you don't think that's the cause you may want to check for slop in your steering links, tie rod ends, ball joints, and track bars. At speed a worn shock could cause issues as well.