Took some time to play with the thermoswitch up front in the
radiator.  Took it out and plugged the radiator with a junker known
not to work.  Turned on the ignition and becan to slowly heat up the
thermo switch with my electric heat gun to see if it would do both
Stage 1 and stage 2 fan speeds.  My 5-6 year old resister behind the
headlight looked fine.  Sure enough, the first stage kicked in and
shortly after so did the second.. After the test, I noticed a white
powdery substance on the sensor-side of the switch.

questionis:  Is this a sign I've got crap clogging my radiator, or
did the relatively quick heating of the brass end with the heat gun
cause residual coolant to turn this color?
I  haven't taken the van out on the road to test the overheating in a
week or so, but the fact it was holding a 103 degree C temp on the
highway, tell me it's an airflow problem perhaps.  I guess it could
be a weak water pump, but it's not weeping and not all that
old.  We'll keep playuing with it I guess.

Max