I've been trying to get through New Jersey emissions for the past few weeks. After failing twice I checked my O2 sensor and found it was completely unresponsive. I ordered a new one and went to install it today. I found that the sensor wire (black) had somehow been disconnected. So I repaired it and checked the duty cycle. As soon as I hook up the meter it reads about 30% and climbs steadily all the way to 98.5% where it remains steady. I'm using a Sears DMM with duty cycle. If I connect red to pin 3 and black to pin 2 I get a steady 98.5%. If I only connect the red to pin 3 I do get a fluctuation between 21% and about 47%. If I reverse the leads in pin 2 and 3 the readings also vary between 21 and 47%. The problem is the readings don't change when I turn the mixture adjustment. It does affect the running of the engine but not the reading on the meter. Also the car is now really hard to start and has no power. I can't rev the engine past about 2K rpm even in park. If I go richer on the mixture I get black smoke from the exhaust but will rev to about 3k. Leaner results in even less power and a horrible stumble just off idle. The car is not driveable right now because if I step on the gas it backfires. The only thing that was touched was the O2 sensor. The car ran with the sensor unhooked, but felt a little sluggish because it was running rich. It idles fine. Any suggestions?? Where do I start??

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