I think '97 was the last year to have the little IAC motor.
These motorized throttle bodies are sensitive to battery charges. Meaning a weak battery can cause idle issues, a dirty throttle bore can cause idle issues.
When the electronics fail, then yes, off idle issues can also surface. If you only had an idle issue, then cleaning the throttle and performing a throttle adaptation / alignment might be all that is needed (same for after a low charge battery issue).
Not knowing what the exact code(s) is / are, it is difficult to take a guess as to what the problem is.
"Generic" scan tools might not show all codes that are stored in the ECM. VCDS (Vag-Com) is the best aftermarket "dealer equivalent" scan tool that is available to the general public. A bit expensive but worth the money if you plan on maintaining the car yourself.
I am not affiliated with the makes of VCDS. My user name just happens to include those letters.
Thomas
Wednesday, May 21st, 2014 AT 9:19 PM