Grease Monkey here again. We figured out that it was nothing more than the O2 sensor. I'll make a long story short to save you all some reading.
We first thought it was the TPS (Throttle Position Sensor) so we tried replacing it.
Then since the TPS didn't fix the problem, we put the old one back in and returned the new one.
Next we replaced the O2 sensor, this made the problem better, but didn't totally resolve it.
Next we checked the ECM codes, we found that the O2 sensor and the TPS were both malfunctioning. Which was strange since we just replaced the O2 sensor.
So we reset the computer (disconnected the battery) and tried it again, this time only the TPS was broken.
So we took the car to a shop and had it calibrated (Yes, they must be calibrated, the Chiltons/Haynes guides neglect to mention that).
Ca-Ching! Problem solved. It turned out to be nothing more than the O2 sensor, but since we had screwed up the TPS'* calibration, we caused the save symptoms elsewhere. ARGH!