Yesterday I brought my car (92 500E / M119) over to have it smogged, it passed without a problem but a couple of things cought my eye and I'd like to get a techs opinion.

I was comparing the results of this smog and my last smog a couple of years ago and I noticed a significant increase in the amount of HC's (Hyddrocarbons) especially at idle (643RPM). I also noted that my idle was lower than the last time I had it checked (667RPM). Are the two related? I want to keep the car at it's peak so knowing what the cause is would be helpful. Anyone have any ideas or suggestions where to look? I assume a higher HC amount means it's running rich?

Some history: The spark plugs are relatively new (4000 miles) and the oil was changed recently. The gas tank does have Techron to clean up the injectors and fuel system, can this be a possible source? The caps/rotors have not been changed and the car has had about 10K miles added since the last smog. The caps/rotors were changed at 44K, car has nearly 66K, is this a possible cause? O2 sensors are the same and I haven't done much else other than strict maintenance.

Is it possibly my idle control valve is worn?

Is it possible that using two different test stations can results in these kinds of measurement differences?

Any help would be appreciated.

__________________
Afshin

Current:
02 C32 AMG

Previous:
92 500E
84 190E 2.3 5 Spd