Idles fast when cold, then idle pulsates up and down. This problem makes it hard to stop and can not find any auto books on mazda that help determine the solution. You start up the car in the morning and the idle revs up to 2000 rpm then after it worms up alittle it drops to 1000 rpm and every second revs back up to 1800 rpm. Then when you put it in gear it appears to stop pulsating but idle remains high making it hard to fully stop. Once it has wormed up to a hot enough tempurature you can shut it off and restart and it then begins to idle correctly. It is very unsafe to drive in the winter with the high rpm's. Any help would be appreciated!