308 cold run actuator intermittent

I don't think that that symptom can be caused by a corroded connection, but a thermal switch that was (wrongly) closing occasionally when cold would give that symptom.

To test, measure the voltage between the two terminals on the small electrovalve controlling the application of vacuum to actuator on the cold start air valve (see Fig 60 of your OM) -- if the voltage is always ~0V when cold and always ~+12V when warm, that would confirm that everything in the electrics was OK, and you'd have to look elsewhere (bad vacuum lines, bad electrovalve, bad cold start valve, etc.) if the fast idle was inconsistent when cold. If the voltage toggles between 0V and +12V when cold (and corresponds with fast idle and no fast idle conditions), that would indicate that the thermal switch is wacky.

 

Steve, what makes you think the cold start valve is cycling on and off?

When operating properly, the csv opens only for about 4-6 seconds upon initial start then is closed thereafter. The warm up regulator is really doing the work of managing the fuel/air mixture throughout the warm up process by way of increasing fuel pressure while the engine is cold. The WUR has several inputs affecting the fuel pressure, and therefore, fuel mixture, coming from the fuel distribution block.

As mentioned above, check the electrics and see if you really do have a cycling electrical signal to the csv. I suspect there's more to it than simply a failed coolant temp sensor. If you're having trouble tracking this down, there's a very good Bosch CIS tuning book produced by Bosch - Amazon has it in stock. Persist and good luck!