[s-cars] Emissions Test Failure

[Kaklikian, Gary]

My '92 S4 failed  the emissions test, in particular the hydrocarbons at idle were very high. All other readings (CO,CO2) were normal at idle and at 2500rpm. The car has had a stumble off idle recently, so I suspect it may be running rich at idle. I checked the throttle switch per the instructions on S. Mockry's site, looked for vacuum leaks, and pulled the ECU codes, all to no avail.
Anyone encountered a similar problem?

Thanks,
Gary