1994 Metro Codes 46 & 51

[udel]

Hi,
The check engine light in my Metro is staying on, and I checked the codes that are showing up. There are two (46 & 51). I believe one is the EGR valve and the other has something to do with the idle. I took the EGR valve off and cleaned it all out. Put it back on, and reset the check engine light. It didn't take long for the light to come back on, and it showed the same two codes again. Does anyone have experience with this, and have any suggestions?
Thanks for your help,
John