Keith, it could still be O2 sensor related. Disconnecting the O2 sensor
does not preclude this possibility. The ECU must see reasonable readings
on the O2 wire at the ECU connector even if the O2 sensor is unplugged.
If that wire is broken or shorted to ground or to some other wire
anywhere along the way the ECU will react badly. The ECU ignores this
wire until the Temp II sensor tells it the engine is warm enough. Then
it uses the reading on that wire to adjust the fuel mixture. If at that
point it sees a shorted wire it will go haywire on the mixture
adjustment at that time.

Unplug the O2 sensor and the ECU. Use an ohm meter to check that the
wire is all in one piece from the O2 connector to pin 2 of the 25 pin
Digifant ECU connector. The use it to see if that O2 signal wire is
shorted to either of the 2 white heater wires.

Mark

Keith Adams wrote:
>
> I checked the Temp II sender and it's within spec at ambient and operating.
> Tried the O2 sensor again (didn't help).  The next odd ball thing I'm going
> to try is the the throttle position switch sticking closed when the
> throttle is open.  It smells a little rich, but hard to tell.
>
> The thing that bugs me so much about this is that it's not when the van is
> sorta warm, but it only happens precisely when it gets to operating
> temperature - no sooner.
>
> -Keith
>