Hi everyone! I'm the ecstatic new owner of an 85 Alfa Romeo Spider Graduate. Car runs and drives great, was garage kept, and last owner did an okay job at keeping it driving strong (sort of a partial restoration). Unfortunately the vehicle will not pass Colorado (Denver Areas) tight emission and fails for high HC and CO out put. NOX is great. Have taken the car to three shops and mechanic will not touch the thing! I went on this thread and found some great info to get me started with the trouble shooting -running very rich- and so far have changed the spark plugs, which yes were full of soot and the number 4 wasn't gapped correctly. Surprisingly car ran better and had it re tested. Still failed for same reasons but now the HO is only failing slightly instead of double the limits . Now I read that when the O2 sensor fails the cars from this time are designed to automatically run rich so as to not cause any catastrophic failures in the block. I have one on order and it looks like it has never been replaced and the car has 160,000 miles. While I'm waiting is there anything else I should check for? Ive looked into changing the air temp sensor but honestly I cant even find a diagram of where it sits let alone any working manual for the vehicle. Any help would be greatly appreciated. I can't wait to get back on the road and get some time in before the real winter rolls in.