The 2-3 shift is controlled by the k-1 valve. Replace the k-1 spring kit then look on this site for "adjusting the transmission". There is a very good write up about it but first replace that spring, it's an easy diy. After you get that done then do the adjustments and it will probably take care of your issues. One thing, before you start adjusting get a vacuum guage. I got a vac guage and connected it in the line to the transmission then ran a line out under the hood and in the passanger side window with the gauge on the end so I could see what was happening when I tested it.
I just noticed a couple of posts down was the write up on adjusting the transmission. Here is the link
http://www.peachparts.com/shopforum/showthread.php?t=158216