The saga continues...
I spent most of the weekend looking for the source of my problems. Found some interesting things, but not the solution. Need some more advice:
First went looking at the 02 sensor. The ECU is not supplying current to the heater, and doesn't appear to be reading the sensor either. The sensor itself tested good, but when I connected a 1.5V battery to the input and ground terminals going to the ECU, I didn't notice any change in the engine. (I understand the engine is supposed to go lean, to the point of almost killing it.)
So is this a bad ECU? I tested for continuity in the wires leading to the ECU, and they are all fine, so that isn't the problem. Do ECUs even go bad? Its all solid state electroincs...
Second, I went looking for my EGR problem. I removed the EGR tube at the intake manifold, and you wouldn't BELIEVE how gunked up it was. I took more than two inches of gunk out of there. It was completely blocked up, and probably had been for a long time. However, that didn't solve my idle problem, which (probably) means it didn't solve the emissions problem, particularly if the 02 sensor isn't being read.