From what I understand the ICV is supposed to compensate for the load placed on the system.
It was kind of intermittent. As it got colder it went from intermittent to constant.
Would that point to a leak? Bad electronic part?
a leak not really, you'd feel that whether hot or cold...
BUT, as you are saying it is sort of temperature related, now I am suspecting the Motronic temperature sensor, the CTS (the blue sensor near the injector).......this one sensor is the most important on the whole system.
Either check it out,check the plug pins are good, or replace it....the ohms tests are not 100% proof it is good, as the probe can get crudded up and under operating conditions sending false info to the ECU.
Motronic CTS (Coolant Temperature sensor): Bosch 0 280 130 026
@ –10°C the resistance should be 8.3 to 10.5 K.ohm
@ +20°C should be 2.2 to 2.7 K.ohm
@ +80°C should be 0.28 to 0.36 K.ohm