I had a similar no start problem a couple months back where it died as you described then wants to start but only runs about 3 seconds. My problem was the intake boot to the throttle body had popped off. Try checking that and look for any leaks in the intake system
I am new to this forum and I want to install an air oil separator on my 05 Mustang 4.6 with a procharger my question is I want to use a 3 port separator can I plumb both inlets on the aos from each of the valve covers and then go back into the plenum. Where I love I have to be emissions...