Re: 92 mustang
if your at a trade school, then they should have access to the full factory manuals....well my one did.
EGR stands for Exhaust Gas Recirculation. Now if there is a problem with this, then it could be constantly circulating exhaust gases through the system...and that wouldn't be helping at all.
One of the biggest enemies of pollution gear systems, is the carbon build up in all area's of the engine....thorough cleaning is constantly required.