Yes, they can go bad.
But...unless you installed one on your truck you don't have one. Diesels don't have a throttle plate, therefore they don't have them. Only on built diesel motors will they become somewhat of a necessity.
You probably have a boost leak (obviously) somewhere. Check all lines, plumbing, etc. If you can fab a 2L bottle over the air intake and seal it with duct tape and then seal an air hose onto that you can make a booty fab boost leak checker. You probably only need 10-15 PSI to check for leaks.
Last edited by GreaseMonkey; May 2nd, 2013 at 09:11 PM.