Like Pdad said, the 91-93 digital EGR'* can usually be fixed by cleaning and lubing the solonoid shafts. He saw this first hand on my car at Woodburn while we were prepping for the track. I used some No-Touch rain shield to free it up and clear the code
It'* a good thing, too, as the digital EGR'* are very expensive, and hard to find in wrecking yards, considering the limited years they were used. I've never heard of one making loud noises, though. You may want to check your evap canister solonoid (disconnect it and see if the noise goes away) or remove your oil fill cap and check for the noise (lay a rag over the valve cover to prevent oil spatter). If the oil fill cap solves the noise problem, replace the PCV valve. It'* under the SC cover, towards the rear of the top of the blower casing under a black square cover.