Dave,
You mentioned your cooling fan....
How is it wired to the 12 volt source?
The reason I ask is how I found mine wired. It was not thermo controlled, but ran all the time the ignition was on. The wiring was too small for the current demands, and the switch warmed up too (heat = voltage loss). I wound up with just under 10 volts getting to the fan motor, with the engine running. Rewired the fan using a 30 Amp control relay, 12 gauge wire to the fan relay (relay only 6 inches from fan) and now I loose just about .3 volts, fan runs FASTER and I immediately noticed an improvement in cooling when the car was sitting at idle. Used to go over 200 to about 210, now runs just a tad over 190.
FWIW.. my 2 cents today
- Jim -