[john]

If throwing coolant in the car causes the light to go off, you have a leak somewhere. There is a sensor at the bottom of the coolant resivour which sends the light on. You need to find your leak. I am guessing it is not the coolant temp sensor.

Vfaq has a idle surge check list which includes boost leak test, BISS oring, ISC testing, etc. Find the coolant leak though. The car will normally idle higher to warm up initialy.