don't scare me now. it's in new nj with the new strict controls. it's registration is current and i think the last tune-up might have been 2 yrs ago. can you qualify what you mean when you say "A car that passes that test with only a set of spark plugs added, has serious problems"? if the plugs are bad, will the lambda feedback control and three way cats clean up the excess HC?
i know that copper plugs go south within a year, because it happened to me. i mean i didn't have all the fancy emission controls on the other car but it was the exact same sort of readout and the new plugs fixed it. everything else passed - smoke and CO. it's only the HC that flunked which is kinda indicative yes?