2002 Ford Escape XLS 5 Speed Engine Knocking

My timing belt was just replaced along with the timing idler pulley, timing belt tensioner, serpentine belt, tensioner and idler pulley, spark plugs, and valve cover gasket. It drove great yesterday but this morning when I was taking my son to school the engine started knocking. It does this idling and at slow speeds. Once driving the noise disappears. Does anyone have any suggestions on what this may be?

Rattle? Clatter? Ticking? Metal-to-metal knocking? Regular? Irregular? Can you post a video with the noise?