Here is something you can check, this happens if you try to use Internet sharing without an Internet sharing plan, go to start/settings/connections/connection/manage existing connections. Here is what I have:
See the phone as a modem, if you don't have an Internet sharing plan you don't need that, so delete it if it is there. If that's not the problem you could try client-Initiated IOTA, next time it wont connect go to start/settings/personal/phone/Internet and click on the start button and see if this fixes it. Last thing I would try is delete the Sprint PCS from connection settings and re make it, this would at least insure that your sign on is correct. If none of this works I would call Sprint and get at least a level 2 tech to troubleshoot the network connection on your Touch. Sprint techs should be able to tell you if your Touch is defective. Hope this helps, good luck,
Dave~