I know from the archives that the dreaded disease is usually either:

a) the 02 sensor
and/or b) the AFM harness upgrade

If I disconnect the 02 sensor, will that make the problem temporarily go
away? I had heard that this is a test to confirm the problem is the 02
sensor.

I disconnected the 02 sensor and it didn't solve the problem. My van can go
intermittently for a quarter to a half a mile before it loses power, spews
some blackish smoke, and operates at about 1/2 efficiency.

If I turn the engine off, then on again, it solves the problem for the
moment (100% of the time!), only to return again within 1/4 or so of a mile.
Seems whatever it is gets reset when the engine is turned  off

Thanks for any advice.

Bill