I have a 2008 toyota yaris that idles rough on a cold engine. It almost feels and sounds like the car is about too stall. As the engine warms up, the idle gets better and the car runs well. I changed out the plugs, installed a new air filter, cleaned out the air intake housing, and i replaced the mass air sensor . I tried new and used mass air sensors and doesn't cure my problem. I also use Lucas injector cleaner once a month as well. I need to know what is causing this to happen. Your feed back will be well appreciative. thanks... Jay Strano