I have a Renault Clio 2002 and when started it idles at 3000rpm I have been told it could be a issues with the coolant temp sensor as it tested at -30C.
Fuel injected motors have a fuel map in their ECU- quite literally an X-Y grid of ratios of fuel to air that will be fed to the engine. On one axis is throttle position, the other, engine RPM. Those two values determine A/F ratio.
In addition to this, there is a "modifier value" to the cells in the A/F ratio table that richens (adds more fuel) for different engine temperatures. So, when the engine is at -30C it adds, say, %30 more fuel per injection; at 0C, 15% more, etc. If your temperature sensor constantly says it's -30C, your vehicle will always run with the cold engine A/F ratio modifier active. That will give you high idle.