The Nav screen on my Sync 3 system seems to lose time with the map.  Cross streets and route curves appear on the screen 7-8 seconds before they actually appear.  This causes the system to show me cross country when there is a curve and we take that before we have arrived.  Not a problem that occurs all the time, but comes and goes.   Ford Dealer expert's only comment on the nav problems was "It works".  Any thoughts on a reset of some sort.