The PCV valve is a bit of a pain to reach,however they usually don`t go bad.Clean it out with some aersol carb cleaner.
The more critical part,(that can cause problems) of the PCV system for a higher mileage 5.0L is the crankcase breather element thats under the rubber grommet that the PCV valve fits in to.It`s basically a small round metal contraption with fine wire mesh inside that can become plugged up over time.
You kind of have to fish it out after removing the PCV rubber grommet using a tool of some sort with a small hook or use a long larger diameter wood screw and thread it in and pull the element out.
Again with the upper intake installed,it`s more of a pain than just getting the PCV valve out,but this is one item that should not be overlooked.(lots of people don`t even know it`s in there).
If your breather element doesn`t look that dirty,they can be cleaned by soaking in solvent,(acetone),etc.If it`s really plugged/caked up with crud just by a new on from Ford.They are cheap to buy.
