That's the Idle Air Controller valve, and it can be cleaned and disassembled (or at least the one used on the 91+ Escort can).

Instructions for reading the codes are here:

http://www.dalidesign.com/hbook/index4.html

I highly recommend spending the $30 on the full version of this handbook instead of the scan tool (since you probably don't need it)--this handbook has been VERY helpful to me in troubleshooting problems.

Brian