Although his swing looks a little loopy Jim Furyk is a great example of a one plane swing, he takes the club outside coming back but his delivery position is exactly on one plane.
Sequence your spine correctly during the backswing, rather than your hips and shoulders, by using this rotation exercise
Many slicers hit the ball to the right simply because they are lined up to the right, when they go to hit the ball their mind knows the target is to the left and then subconsciously changes the swing to outside in so that the club travels towards the target causing a slice