vaccum line missing in back of manifold against firewall cant figure it out

There should be a vacuum diagram on the hood of your expedition. There was when it left the factory, this is what is use in the shop/ If it has been painted over due to an accident, then I go to alldata, you can go to www.alldatadiy.com and subscribe for your car, it is very reasonable. There you can access all the diagrams that you need, including the vacuum diagrams.

sounds like pcv valve its located on passenger side valve cover has plastic tube connected to it follow hose till you find the end might wanna get that fixed can cause sludging inside your engine and oil leaks cause crankcase cannot ventilate without it