Zen Golf is a good book, at least it was for me. Have you tried not taking a practice swing? I don't usually take them unless I have to stand around for a while, I just swing the club around to stay loose.
Quick question - how do you know that your practice swing is more powerful and on plane? I actually think that my practice swing feels better because I have no ball flight to reflect the flaws. What usually helps me is creating a simple routine and sticking to it. Also, use about 40% of your total effort on your backswing and through swing. I struggle with the same stuff you are, for me it is all about slowing myself down.