I know the feeling! Getting a smog check is like going to the dentist...you just hope you don't have to come back! My 83 245GL failed a "test only" smog check. I wasn't really surprised, as it had a high idle when I bought it and some other little issues. The car ran great and was dead reliable until it was hit. I don't remember my readings, but I think it had a high NO or something. After the test, I changed the oil, oil filter, spark plugs (don't use platinum plugs!), cap and rotor, did an engine flush (2x), and checked and tightened all hoses and clamps. I took it to this that my sister suggested because this guy she knows work there. He did a preliminary test to see if it would pass...it didn't. Anyhow, going there was a waste of my time, and that guy kind of pissed me off. He did adjust my idle and suggested that a new cat might be needed. He said he'd charge me about $200 for a new cat and installation. Hell no. I paid a little over half of that amount. Out of frustration, I took it to a cheap muffler shop and got a generic cat for $75. The car passed.