try this to clear the EGR flow
malfunction. You will have to clean out the "pipe" from the egr valve to the intake manifold. This can be as simple as "rodding" out the line from the egr valve to disassembling the connection at the intake end and cleaning it out. Do a search on EGR and you will find this thread.
The other (I would imagine) has to do with your air pump system, maybe the line plugged or the pump inoperable. Wait for someone more knowledgeable in this regard to answer this one.
'85 300D - no check engine light