Wondering if anyone else has had this problem or a solution. In NAV mode (GPS or ILS in particular, haven't tested with VORs), I'm getting a slow oscillation left and right. The autopilot seems to be correcting for course, but over correcting and going back the other way again. It's within a couple tenths of a mile either side, but the turns every 30 seconds are getting annoying fast. 

Using the PMS GTN650, not sure if that has any effect.

i've not noticed that, but I did notice that the AP struggles to hold the ILS glideslope. kept dipping far below so much I had to take manual control as to not run into the ground.