Did it fail at idle or at speed? The EGR ports on the intake are prone to clogging, remove the EGR and check the ports. Make sure the cat is hot as hell <img src="/forums/images/graemlins/evil.gif" alt="" /> 30 minutes of hard driving and don't let it cool down before testing.

Last resort,

I'm sure you can pass with "special gas" run it down to 1/8 a tank and add a gallon of denatured alcohol from the local hardware store. Get it checked and then fill up, you don't want that strong of a concenstration in there for long.

<img src="/forums/images/graemlins/cheers.gif" alt="" />