1999 Ford Mustang V6 Starting Problem

Any help would be greatly appreciated:

My 1999 3.8L V6 Mustang has recently completely stopped starting. It had some difficulty starting for about a month and now it no longer will start at all. The engine turns over fine (the starter sounds great); I had the anti-theft system checked and the keys are set to the vehicle; I took the car to the dealer and they told me that it was the ignition coil pack - I replaced the coil pack - the vehicle started once (I drove it down the block and back and shut it off - and it would not start again). The vehicle sounded fine when it ran )during the month that it had trouble starting, and when the vehicle started after I replaced the ignition coil the vehicle seemed to run fine. The dealer told me that the gas pressure checked out.

I initially checked and changed the battery and cleaned the cables that connect to the terminals!

Because it runs fine when it finally does start makes me believe it is not a gas/air problem OR a spark plug/cable/coil problem. I just don’t know what else to do…

“My 1999 3.8L V6 Mustang has recently completely stopped starting.”
"Because it runs fine when it finally does start "

Just to clarify:
So you can get it started but it just takes a long time to get started?
Or it truly does not start at all now?

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.

I know your coils have been replaced but have you verified that it has spark?
If so, what happens when you spray some starter fluid into the air intake? Does it want to start at that point?

I am unsure how to check for spark other than to hold the cable while someone else cranks it. I had originally been under the impression that b/c it did start and run once there should be spark. That being said - I should check the spark and I will have to go and get some starting fluid.

If you have a pepboys or napa nearby, they sell this cheap widget that a spark plug cable plugs into and you clip onto the engine or ground. Once you start, it will throw a spark across a gap.
Since you replaced the coil pack, it could be that the old pack did damage or maybe the new coil pack is damaged. In other words, the bad coil pack may be a symptom - not a cause.
That’s why it is important to make sure you have spark.

Edit: here’s the one sold by autozone

This one seems to plug in series with a spark plug.

Here’s the one sold by NAPA.
This is the one you plug the wire into and clip onto ground.

Thanks a lot. I’ll update once I have this completed.