:whs: It seems like your 5 volt reference is shorted somewhere or just plain low. Do you have a voltmeter? Pull the ICP sensor plug and measure the voltage on Pin 2 (Bn/Wh wire). It should read 5 volts. If not, then there is a problem with the harness or ECM.
The only way to test the ECM is to pull the middle connector, remove the Bn/Wh wire from position 36, replace it with a test wire and then reconnect. If you are now getting 5 volts on the test wire, the ECM is okay and there is a short in the harness or one of the sensors pulling the voltage down. At this point, do NOT use the ECM as a power source to locate the short. It will damage the regulator in the ECM and will render it useless.
If you determine the ECM is fine, you'll have to start hunting down sensors and disconnect each one until the problem goes away.
Happy hunting.