Will not start sounds like it wants too but doesn't.

What is your question?

i have a 2003 dodge 3500 van 5.9 won't start. codes po 340, po 645 and po 523 come up. I just gave it a mini tune up plugs and it ran for a day. now i changed cam postioning sensor still no avail. I just prayed starter fluid to see if it was fuel pump still not even close to starting. I'm lost please help.