Zig zag on dirt road

Hey all, haven't had the bike long. It's a 2013 sportsman 850 xp with a 3 inch lift 2.5 inch stretch on 33 bkt's. I'm just wondering if a bike with this big of tire always ride like crap on soft loose dirt? Like it legit swerves all over the place at 25mph. It's pretty sketch to be honest. On pavement it doest swerve near as bad buthing does a little and the handlebars shake pretty food at 35. I haven't been over 40 because of this. Don't really need to be going fast but I would like if it didn't swerve or shake. Anything I can do?