This may be a contradiction in terms, but limiting the amount of moving parts in your golf swing actually increases the power you can generate.
As TG Elite Pro Rob Watts explains in this golf video tip, moving your head up and down or side to side actually means you rotate your upper body less, which means you create less coil.
The trick to create maximum coil is to keep your head relatively still from the start of the swing to the point of impact, rotating your upper body around your spine.
This tip will also help you achieve a strike out of the centre of the clubface for more consistently.
You can try making some swings up against the wall to achieve the same feeling of the head remaining static during the swing.