Details on engine codes for a 1992 Crown Vic?

With the 172 and 176 it sounds like it has a vacuum leak, either a vacuum line going into the intake.Possible Maf sensor has gone bad, or their is a intake manifold leak.While engine is running, take a can of carb or brake cleaner and spray around the intake manifold, if you hear any changes in idle, either reving, or decrease in Rpm there is a vacuum leak.It would be easier to detect with a scanner, to moniter the short term fuel trims.With the egr it could be either the egr it's self is stuck, or it could be the DPFE sensor which relays the signal to open and close from the ecm.GL hope that helps