There was a post some time ago about using a heavier spring in the shift knob to avoid this, that included some great instructions, as well as part numbers for making the modification - wish I had time to look it up, but I don't. Not sure the best way to try to look it up, but the post was very thorough in its instructions and should take care of your problems - maybe someone here will come forward as the one who posted it...
"If you're not living on the edge --- you're taking up too much space!!"