Strange boost activity.

After changing my filters I noticed that my boost gets to around 4-5 psi when I'm in 3rd or higher around 2100 rpm without my foot on the pedal. Shouldn't it be at vacuum if I my foot is off the gas?

diesels dont create vacuum there's no butterfly valve on the inlet manifold

At O% throttle, ie foot off the go pedal, one would expect the boost to drop to close to 0 psig. 4-5 psig seems a bit high assuming your car is stock and might point to turbocharger vanes sticking a bit.