I had this same problem, really bad through the 2006 season, and into the 2007. I tried a bunch of different releases, and finally settles on a Carter Chocolate Addiction. Different releases seemed to make me punch less or more.
Another thing that helped me was to set up a target in my garage. Draw the bow, with an arrow nocked, settle the pin on the X. Count 5 one thousand and let down. Do this over and over and over, then do it some more. This trains your brain, that you don't have to fire as soon as your pin and the X cross paths.
Really helped me a lot.
I wanna try one soo bad just for the heck of it. I would shoot up scores every week lol Im sure id still find a way to punch it lol. j/ki just started using a hydraulic release and has worked wonders when i swith back to my strap style release, the nice thing about a hydraulic is you never know when it will go off so you cant punch or panic, it is actually kinda soothing.