The O2 sensor- Heard there is supposed to be a tool one can use to test the O2 sensor-something not that hard to use and portable. Anyone know about this? Thanks.

You can use a $10 multimeter to verify that the O2 sensor sweeps through the .1 to .9 volts it's supposed to. An Oscilloscope or Dwell meter can be a lot more useful, but they're not very portable or anywhere near as easy to use as a multimeter.

Just set your voltmeter to 12V (so you don't blow your meter if you hit the heater wire), touch the probes to the sensor connector and a body ground, and you should see the needle move a a tiny bit. Then switch your meter to a lower volt reading (maybe 5V or 1V) and check to see that the needle sweeps smoothly up and down and doesn't stick anywhere.

You can open the throttle a few times and see that the voltage changes a few times as a result.

Happy Bricking
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1990 740 Turbo, on its way to stock specs, maybe beyond