Check engine light issue - need help!

Have a 2000 Tacoma 2x4 reg cab with 27,000 miles and California emissions. It's been off the road since 2004 and I want to put it back on the road.

The truck starts and runs ok until it warms up....after that it idles around 1300 rpm.
The check engine light was on and I had it scanned at the local Auto Zone with the following results (three fault codes):

P1135 Air/fuel Sensor - Probable Cause
- Open short circuit condition
- Poor electrical connection

P1130 Air/fuel Sensor - Probable Cause
- Open short circuit condition
- Poor electrical connection

P0125 Insufficient coolant - Probable Cause
- Faulty thermostat
- Low coolant level
- Faulty ECI

Note......for fault#3 the temperature gauge is normal, coolant level is normal, and more than enough heat.

Everyone I talked to suggested replacing the upstream oxygen sensor....I did and it did'nt solve the problem!

I'm thinking there is a wiring problem between the front oxygen sensor and the computer but I don't have a schematic. Am I on the right track? Do I need to bite the bullet and go to the local Toyota dealership?

NEED HELP!!!

bojo