GW,
Try what I said, on the first move of your downswing deliberately focus on the ball. This will keep your shoulders square. You will not come out of your shot too early. Trust it.
Swing at speed that you can hold your finish, until to ball first hits the deck. If you've swung too fast you won't be balanced.
Increase the speed of your swing mid way down from the first motion of your downswing. I know that I have problems at the top when I try and rip it.
Like Ernie said in his last digest article (aust) think smooth at the top of the downswing.
GW try this with a 9 iron. The shorter
irons are alot easier to use when practicing swing changes.
VP