If GIXER7502006's advice does not work, take the switch back to AutoZone (if that is where you got it), and go to the Ford dealer or NAPA at least. AutoZone does not sell anything worth buying except oil and filters. That is in my humble opinion.1990 mustang 5.0 I have replace ingition switch and colum and I still get the same results. The engine will fire but not stay running unless you hold the key just off of start if you let it return to run it will die. please help