Engine Idle

I have a 1999 chevy Malibu that has an intermitent high engine idle 2000-4000 rpm. This had been happening dialy upon startup and not coming down. Turning the engine off and restarting sometimes made the engine idle in the normal range (700-800 rpm). The throtle cables are free moving. Any ideas??

There several things that can cause this but the main ones that come to mind for me are the throttle body gasket, vacuum lines and the O2 sensor. To test the throttle body gasket you can spray some choke cleaner around the throttle body when its running. If the engine surges then you know you have a leak. If you have a leak then unmetered air is entering the system and the O2 sensor will register a lower voltage, causing the ECM to increase fuel to the system, yielding a faster idle. If one of the vacuum lines has a leak in it, it too will send inaccurate data to the computer. If the O2 sensor is bad, then it can be registering a lower voltage all on its own. Usually you start to notice a bad O2 sensor with decrease fuel economy, lumpy or fast idle or decreased engine response. Without a multimeter and an O2 connector, and a vacuum gauge, you can't really test the latter two problems easily. Perhaps others in here will have better suggestions or you can bring it in to have it looked at. Good luck