Here's the update on the surging idle:

I took off the wire harness to the ECT sensor. (It has a black connector, right?) I measured the resistance across the sensor, and it was right around where it should have been. (Interpolated between the two values listed in the FAQ:
http://www.brickboard.com/FAQ/700-900/EngineSensors.htm#DiagnosingECTFailures )

The next thing I did was to take off the ecu and test at the connector. I tested the voltage between 16 and 5. The procedure said that 5 was ground, so i just tested between 16 and a ground on the frame. Was this substitution ok? My meter showed no voltage. Next thing i did, per the FAQ, was to check the resistance between 16 and 5 with the sensor disconnected. The FAQ said it should be infinite, but my meter showed a hell of a lot less than infinity.

So, from all this I'm thinking that it might be a wiring harness problem. This pisses me off, since i just replaced it two summers ago, but I guess things happen. Any ideas?

I just read Bruce's post (http://www.brickboard.com/RWD/index.htm?id=679686) after typing all of this in. Is it possible that the test i did was wrong for my car? (I know i didn't do a great job of testing for voltage) Also, is it possible for the sensor to have the correct resistance but not the correct voltage? I'll have to try his test when i get home tonight.