1999 Ford Mustang V6 Starting Problem

To clarify: I had difficulty starting the vehicle for about a month until it completely stopped starting. During that month of difficult starting, after it did start it ran fine. After the vehicle completely stopped starting and I took it into the dealer, I was told I needed to replace the ignition coil. I did that, it started once (and sounded fine and ran well), and after that I have not been able to get it started. It has fuel.