bad idle, variable to temp outside

[Pimpin Dsmstyle]

My car runs like shit until it gets to temp, then it runs fine, but surges. The surge is weird because sometimes it is from 1k-1.5k, sometimes 2k-2.2k etc. Really changes. I noticed that below zero its ALWAYS around 2k surge. When its around 20 out, it stays below 1.5k. Every once in a while, I get a coolant light popping on. I pour a little in and it goes away. THIS ONLY HAPPENS WHEN IT SITS OUTSIDE IN THE FREEZING COLD OVER NIGHT. This does not happen when it sits in the garage. My question is this, could the coolant temp sensor cause this problem? I do not get a CEL at all. Thanks.

[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.

[Pimpin Dsmstyle]

As it gets warmer, it idles higher. Today it was quite low. It even broke lower than 1k. Probably was because it was a little warmer out today. I have a gasket for the thermostat housing so i might as well get a new one with working sensors!

[slowbubblecar]

you may as well get a new thermostat as well 9 or 10 bucks I think