All new instrument students go thru this, there is a fix for this that I have used for years. Remember that an ILS is nothing more than a Consent Airspeed, Consent Rate of Decent and Consent heading Approach. The CDI just tells you how well you are holding a heading and the Glide Slope how well you are holding a consent decent. So this is what you do, once you establish yourself on the Localizer (Heading) and you start your rate of decent ( Glide Slope) Have your Instructor cover the CDI and you just fly the heading and rate of decent, every 15 sec or so have your Instructor uncover the CDI and you look to see how well you are doing. This will force you to fly good attitude instrument flying. At first it will be a little weird, just like partial pannel, but after a bit your ILS's will settle down and will be were you need them to be. A good place to do this would be in a Simulator then some pratice in an Airplane or Helicopter depending on what you are flying. With in an hour or two you should be all set. The problem here is not with the CDI its your instrument scan. You spend to much time glued to the CDI, so you end up chasing the needles, and it goes down hill from there. Everybody has this problem to one extent or another. Its just a little hump along the way to an Instrument rating.