[wiswind]

"Catalyst Efficiency" is how well your catalytic converters are working.

EGR ports.....These are in your lower intake manifold.....and I have cleaned these on my '96 windstar 3.8L......not as bad as it sounds....and there are threads on here that talk about that.
Also LewisNC has some pictures on his yahoo group.....

MAF...."Mass Air Flow" sensor......this is in the canister that is in between the air filter and the flexible hose going to the throttle body. You can clean this with a non-residue electrical cleaner.
There is a screen.....make sure it is clear of stuff.....and you will see a little plastic cross piece....with an air inlet (facing into the air flow) and an outlet....(Facing away from the air flow)....This is where you want to spray the cleaner.

But....as ModMech has advised....DO go have your codes read at Autozone or other auto parts store....
They will do it for free. And it will help you find your problem.