What should I do about a DUI and failure to appear?

Sentencing will be under the laws in effect at the time that the offense occurred (not the current law).

You need to be aware that once you failed to appear in court for this a bench warrant for your arrest would have been as issued.  Do not ignore this warrant.  The never expire.  While you may not be actively pursued for this, if you get stopped for something as minor as jaywalking or having an employment background check run, this could all turn up.  You will then be placed into custody. This will weigh against you in court.  It would be far better for your to go to court voluntarily then showing up on the jail bus.

You need to get an attorney in the area where the warrant was issued.  They can use their local contacts to your best advantage when turning yourself in.  They can possibly also help minimize the penalty imposed.