Having trouble with a 06 f250 5.4.It set two codes p0171 & p0174.Runs good but seems to studder on acceleration.Checked for a vaccuum leak and didn't find anything.Thinking maybe clogged injector?Any ideas would be appreciated.Also fuel pressure is 40psi.

 

A clogged injector is more likely to throw a misfire, I would check the pcv valve and hose all the way to the intake manifold, no luck look for other means of unmetered air past the mass flow would be intake tube cracks, upper or lower intake manifold gaskets,a air leak that effects both banks