Failed emissions in NJ please help

[voltes v]

Hello,Ok here's the deal. I took my 93 240 to inspection 2 days ago and it failed emissions. Here are the results:

NOx 592 PassHC 194 FailCO 1.70 FailCO2 13.3O2 .5

The car previously had a full tune up 3 months prior.

Afterwards I changed the sparkplugs to Bosch Platinum Plugs and get reinspected. I fail again and now the numbers are higher.

NOx 243 PassHC 215 FailCO 2.20 FailCO2 13.6O2 2.1

The guy said something about the levels were going up and down, sometimes low and then really high but car was idling normal at 900rpms.

I need advice on what I should do, NJ has this thing now that all repairs have to be done by specific facilities, but I don't want to pay through the roof for repairs. My other choice is to do the repairs myself but I have to supply all receipts for the parts replaced and used. The check engine line does not come on and car runs smoothly. The last thing I did was to clean out the throttle body/plate cuz the car kept dying after switching the clutch to neutral. I thought for sure the car would pass cuz the idle was good and no more black smoke during startup I think. I do have a feeling the car is running a little rich cuz gas goes down faster I think but I'm not positive. Any help will be appreciated.

Thanks

[s13sr20chris]

yeah, your a little rich bro. start by going back to ngk plugs. then you need to check the maf signal. do you have a voltmeter? if so check the voltage at all the maf terminals and post them. a bad o2 sensor will cause a minor rich prob like that too. if you want, i have been told that a new cat and 1 gallon of denatured alcohol in the tank will clean up most rich probs.