2.0l turbo "auto" gas. Coolant light was coming on when cold "blue" resulting in car stalling when coming to a stop. Once the engine is warm does not happen. Then the light remained on permanent and gas consumption terrible. Temp sensor has been replaced yet the car still stalls when cold as you come to a stop? RPM idle when cold is about 900rpm and as you slow this dips to about 500rpm and results in stall. Any help much appreciated.