Do you know what the problem is? Are you nervous? Whatever changes from the practice range to the 18 hole "show" is what needs to go.
How about Spring Forest Qigong for peace of mind. We both know everything in life has a mental aspect and golf is no exception. By quieting your mind, the mechanics of your swing will stay smoother during course play. Trust me the Qigong is life changing, for golf and beyond. Life is sweeter with Qigong, definitely. :-)
~Vegan Forever~