My car is running like crap. I changed the spark plugs, which were real dirty, but it still runs real bad, especially when I start it, it will slow down and almost die, then rev itself back up and then almost die again, again and again. It runs a little better after a while, but not much better. When I take my foot off the gas I hear a very slight clunking noise, sometimes with a rattling. And the exhaust smells rich. Could I need a valve adjustment? I have maintenance records indicating it happened 10,000 miles ago, but that was b4 this car sat for a year and a half b4 I rescued it. 02 sensor? Or do I need an engine rebuild? Thanks to all...

Nick