Intermittent low idle

Cool, you're on St. thomas! I have a place on Roatan! Also very hilly and lots of people have car problems. I'm very popular when I'm there... OK, first, an oxygen sensor inspection means check the signal coming from it using a high-impedance meter or better a scanner which displays data. Bad O2 sensors will probably cause your computer to run the engine in "Warm-Up Mode" or a default setting because there's no O2 signal. this will foul plugs, cause high fuel consumption and make the engine run bad and wear out quickly. A faulty thermostat can cause about the same effect on your engine. On Roatan and on mainland Honduras I've noticed that people take a hammer to an O2 sensor and take out the thermostat, they think they're onto something because when in Warm-Up mode the engine feels responsive at low speeds but really isn't running well. If your idle is erratic, try removing the Idle Air Control (IAC - I think on the throttle body) if possible and clean out its ports and passages in the manifold. Running with bad O2 sensors and/or a bad or missing thermostat can cause carbpn buildup in the IAC system.