You can try this but I must warn you, it takes a one-time clean install.
- go to Mac: ~/Library/Application Support/MobileSync/Backup/ Windows: C:\Documents and Settings\user\Application Data\Apple Computer\MobileSync\Backup or C:\Users\user\AppData\Roaming\Apple Computer\MobileSync\Backup and delete your backups.
- Restore phone as a new device
- Setup new phone with all your apps and settings
- sync
- return to /MobileSync/Backup and copy the backup to your desktop or somewhere safe where you're not going to lose it.
- Jailbreak
Whenever you want to JB and/or a clean install, you can always go back to your
/MobileSync/Backup, delete the backups that are currently in that folder and drag the one you copied into
/MobileSync/Backup. Hit restore, and select the backup you dragged into
/MobileSync/Backup! That simple.
This should cut the hassle of installing and setting up the phone every time you want to JB or clean install.
Note: I typed this at work so the instructions were rushed. Let me know if you need me to clarify anything.