2005 Ford Expedition

Any suggestions, trouble with vehicle starting mostly in the morning.  Lights
come on, all but when turn the key you can hear a click sound will not start.  
Let it sit til about 10:00 am or so it may start and works fine all day
sometimes days.  It is only in the mornings that this happens.  been at the
shop 2 weeks they can find nothing.  They did notice a cable and he said
they replace that with a longer one thought it fix it it started for 2 days then
right back. please help i did have the signal switched replaced because the
high beam lights would not go out but that is fine could something be missing
there causing this?