I've was dealing with bad carbs, failed emission tests and general crappy running engine since August 2008. I finally gave up on newly rebuilt carbs from Holley, got my money back and bought a carb from the junkyard for $10 and rebuilt that.
What a difference. The engine smoothed out and was pulling 18" of vacuum. But I still couldn't pass the smog test. Spent lots of time trying to clean it up but it still was grossly polluting at idle. Over 1300 ppm of HC. Even my mechanic couldn't figure out why as every test, every adjustment, complete tune up wouldn't clear the problem.
Finally in frustration I pulled the cylinder head and I could see a burnt valve so off to the machine shop I went. One new valve and all reground seats and new stem seal later the car passed just fine. The machine shop charged me $140 and that included all the upper engine gaskets I needed. Oh I forgot to mention that it's pulling 20" now with the valve job.
However, in my opinion it's still polluting too much. The state allows 120 ppm HC and my car measured at 88 ppm. So, next year I'll tune her up again and install a new cat and that should bring it down some more. My engine ran so lean for a while and soo rich for a longer while I've probably coated that cat with all kinds of bad stuff.
I took it down to the Fabulous Fords Forever show last April and it ran just fantastic. What a pleasure to drive. Here's a pic of me arriving at the show and one at the show. I was only disappointed to not have a station wagon class at the show. I was the only Cougar wagon parked with 33 other Cougars. Those folks are not chatty at all nor did any of them come see my car. Lots of other traffic though and lots of good folks I met that day.

