Do you see a TCL error when the connection is reset? If you grep through /var/log/ltm (grep -i 'tcl error' /var/log/ltm), do you see any errors? Are you able to reproduce the issue or get logs from such a failure? I wonder if it's an issue with collecting more data than TCL can handle. If that were the case you should see a TMM restart when the issue occurs.
Also, do you need to collect the response data if you're just trying to reselect a member of a new pool? Couldn't you use HTTP::retry from HTTP_RESPONSE to retry the request without collecting the response payload?
Aaron