i'm really no expert...
but are you using your legs? you can reduce the motion of your arm and gain consistency if you have a good leg bend and direct that energy up into the ball. It might take a while to get the timing right, but this has helped my own serve quite a bit. My wind-up on the serve is not that long, so there is not much room for error, and I still get power from my legs. I also find that nerves don't hurt my serve as much as they used to, because it is a consistent motion.
Also, if you have a classic Sampras form, with the racket "back-scratch" in the preparation phase, you could consider simplifying it ala Roddick, Schuettler and a number of other players these days, who bring the racket up immediately.
other ideas: you could lower the ball toss (Agassi only throws it about as high as the point where he hits it), and experiment with not trying to lean into the court too much/too little.