Idles up and down between 1500 and 2000 RPM. I was told it was the ECM.
There is a possibility that your ECM could be causing your idling issue. However in my experience control modules do not go bad very often. The problem could be as simple as a throttle body that needs to be cleaned or a vacuum leak somewhere on your engine. To either confirm or eliminate the ECM as a problem requires special diagnostic tools and knowledge of the electrical system of your vehicle. I would recommend you ask for help from one of the highly qualified mechanics at YourMechanic to diagnose what is causing your idling problem.