Failed emmisions...help!

[RonE320]

my luck. the gas station in new york that inspected my car ...94 E320 failed me and then had no clue how to fix the problem. so I had it looked at another place....he couldn't do it either but he did offer sound advice. first of all my car at idle revs fluctuates 5-10 but only in the park position. this is somewhat related to EXHAUST EMMISIONS. the vehicle reading reports hydocarbons at 411 ppm and test limits are 220..... co 5.53% vs. 1.20%....co2 12.0 and nox 2%. i might need a new idle speed control unit. i have an appointment with the benz dealer later this week. since the car is not under warranty and i'll be paying out of my pocket i need to make sure that i won't pay for excessive costly repairs.
any suggestions..im glad this site is hear to help. I just want to be prepared. what the heck is that smell!!!!

Happy New Year!!
Thanks,
Ron