With the red/120 ohm temp would creep up to 170-175°F when idling in stop and go traffic. With the white/150 ohm, temp creeps (rarely) up to 165-168°F.I'm surprised you're down at 150°F at steady state and you're not getting a P0128 code. Does your temp creep up that much when idling that you're above 167°F? Sorry, I haven't read all the old posts.
So -- I finally got around to installing my UltraGauge MX 1.3. The Lambda coefficient values of both front and rear oxygen sensors are spot on, cycling between 1.00X and 0.99X. Both catalytic converter temperatures are running at 1,300 to 1,500°F. Temperatures of both engine coolant (150-152°F) and automatic transmission fluid agree with ScanGauge values. Scanning with both units shows no codes, all while using white 150Ω resistor.