Rotten and Coroaded ALDL plug

[noelboy]

Ive been having a lot of missifre issues with my C20LET so thought I'd flash out the stored ECU codes as the EML has been lighting for a few seconds. When I unpluged the ALDL plug I noticed that the socket it plugs in to is really badly coroaded and that there is only 1 pin in there.
Should there be more then 1 pin?
Also what would happen if the ALDL plug is not plugged in when you drive? Could this corrosion be part of the missfire problem?

Thanks