You could try using the free app My Contacts Backup. First use the app the backup your contacts (it attaches the backup to an email, which you should send to yourself and use to re-import your contacts if something goes wrong). Then tap the preferences gear icon on the lower right, scroll to the bottom and tap Remove All Contacts. Now you should be able to sync your Google contact to your phone by setting it up as an Exchange account as explained here: http://support.google.com/mobile/bin/answer.py?hl=en&answer=138740. Finally, to sync your contacts to your computer you'll have to delete the contacts from the supported client you are currently using (e.g., Outlook 2003/2007/2010) except one (leaving a single contact is critical). Now sync your phone and you should get a merge or replace prompt for contacts, select merge.