To the best of my knowledge ALL US version 93 (M104) 300E had air pumps. I wonder where they got the head from?
The 104 predessor 103 had air pump from 1990-1992.
I would definitely take it back to the hackers that did the first repair. It is illegal to disconnect or disable emmissions equipment.
92 Volvo 740 Wagon aka "Mutt mover"