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This isn't a high traffic forum. Responses come slowly from time to time and there is no paid staff, we volunteer our own time to help. Just bumping your original post if you haven't seen a response in a day is better form.

Please post the make and model of the wideband. The power source and grounding of the wideband are critical if you want to avoid false readings due to linear or (worse) logarithmic voltage offsets. Also remember that improper wiring or hardware placement will cause readings to shift as connectors, wires and or hardware are heated up... If any of the wideband's hardware sits in the engine bay you should consider moving it. The preferred ground would be to a stud near the one that the ECU is grounded to on the driver's side of the head.

The torch method of testing isn't the whole picture. The sensor doesn't report with a flat voltage signal, it's frequency must match the IGf signal (with an offset). This is what looking at Vf tells you but they don't explain it well or tell you how to read it even more accurately with a scope on both signals. Really, it's a cheap part an I'd just replace it if you still don't trust it after going through the diagnostics in the TSRM. EDIT: If the ecu doesn't see the correct frequency in the OX signal it will regard the O2 sensor as defective and go into full time open loop operation. The ECU gives the O2 sensor a set period of time to start providing a valid signal before it writes it off. No error code will be presented if I remember correctly.

Unfortunately, I don't know anyone at present who has Toyota's publication on testing the KVAFM with a scope... I really wish I did though. I'm going to have to start asking my friends from a couple dealerships if they can get me a copy.

You may also want to check the ECU for any signs of leaking caps.

I still have no reason to have any faith in your wideband. When cold all of your AFR readings should be on the rich side not stoich; 13.5:1 or so or lower.

I'll try to take a look at the video in a just a few minutes. I have some documents I need to finish working on before a courier arrives for them.

EDIT2: Yes, ANY intake leak between the turbo and the head will leak the most as the intake charge is at a higher pressure. It's just called a boost leak if it's leaking specifically while the system is pressurized. Check for any leaks in the intake and vacuum plumbing. Ok, gotta go. I'll try to get back in a bit.

EDIT3: Don't let me forget to give you a list of what AFR you should see and when. 10 to 12 while boosting is NOT a rich condition. 22 when coasting is NOT a lean condition. 17 while cruising IS a lean condition unless you're feathering the throttle, coasting down hill, etc.