I agree with the poster above.  We had to reduce our angle of turn setting to stop the weaving.  It could also be online aggressiveness.   On a 1980's 2wd we had to lower the angle of turn all the way to 8 degrees.  In my experience, with a lower angle of turn I have to line up the tractor better to "catch" the line, but it will "hold" the line a lot better.  I would mess with it some time you are doing something you aren't in a huge rush on and fiddle with the angle of turn and online aggressiveness.  I'd change mine every pass until I had it dialed in to the best it could be, and then it is fine from then on.