Nissan Repair: 08 Nissan Pathfinder slow to start in cold weather, fuel pressure regulator, crank angle sensor

Question
My 2008 Nissan Pathfinder is very slow to start when it is cold.  Cold being 35 degrees or less.  It has never done this in the previous winters and has been left outside most of those.  I have a new battery 4 months ago and have taken it to the shop and they can find nothing wrong. It will 'crank' and sounds like it is gonna start but nothing.  Sometimes it will eventually start if I just hold the key forward a long time and sometimes it wont.  
I have added fuel cleaner to a tank of gas and that didnt help either.

Answer
Engine cranks at normal cranking speed but it does not start possible causes: Cold start fuel enrichment injection,  defective ignition switch, incorrect engine adjustments, failing Crank Angle Sensor, restricted air and or fuel filters, failing fuel pump relay, faulty fuel pressure regulator, vacuum leaks, faulty fuel pump.
Engine cranks at low speed and eventually the battery dies possible causes: corroded battery and ground terminals, failing starter motor, and faulty charging system.