Often the slice move starts with the upper body first because you are trying to hit your driver really hard. When the body starts first the golf club gets out in front and moves towards the left (for right handers) creating the side spin of a wicked slice.
Instead, go the top of your backswing count to two and begin the downswing with your lower body and as you do you’ll notice that the golf club stays more behind you not out in front.
Starting with the lower body puts your golf club on the right plane which will help you hit the fairway.