Does the Idle nailing ever go away?
Is there nailing after you accelerate?
A small Air Leak will cause nailing at idle.
Worn Injector Nozzles or low opening/pop pressure can cause nailing at idle.
Late/retarded Fuel Injection Pump timing can cause nailing at idle.
If the Injectors have been in use for 150K and never checked it is highly likely the Nozzles are worn out. However, that is not always the case but if they have never been checked it might be time to do that.
Low or uneven compression can also cause nailing but you usally have more difficulty starting in the cold.
All of the above assumes good quality Fuel. Hunter has a thread about a rash of bad quality Fuel that shows up on the front page of diesel discussion today.
More detailed info:
Repair Links
Fast navigation
http://www.peachparts.com/shopforum/diy-links-parts-category/146034-fast-navigation-do-yourself-links.html
http://www.peachparts.com/shopforum/forumdisplay.php?f=82
http://www.peachparts.com/Wikka/DoItYourSelf