New Fuel Filter But No Improvement

For the best help always post the full DTC codes. There are 1000's and they each have a story to tell. But in general for lean related DTC's start with looking for vacuum leaks.

You may not believe this but a bad battery or loose battery connection could cause the motor to suddenly quit. Recommend starting all trouble shooting with a through review of the charging system. Here's some information on advanced charging system testing.

Howto perform charging system voltage drop test
https://www.stangnet.com/mustang-fo...perform-charging-system-voltage-drop-test.56/

Here's a crank with no start check list with some more information:

1996+ Crank with no start check list:
http://www.allfordmustangs.com/forums/4-6l-tech/336452-1997-mustang-wont-ignite.html#2984838

There's a fairly long list of things it "could" be so we need some where to start. That is way I always recommend starting with the basics and then work up. Don't cut corners on the charging system checks. But for a motor that quits while underway my experience tells me this sort of problem is electrical in nature a great percentage of time.

Tell us more about the work done on this car. What have you done to confirm fuel pressure at the rails?

If it still won't start after going through the "crank with no start" check list then we need to know IF there is key on power in fuse F2.34, F2.2, and F2.8. Use a KNOWN good ground. Where to go next depends upon the results.

1999-2004 MY fuse panel schedule:
http://www.allfordmustangs.com/foru...r-swap-wont-fire-please-help.html#post2669271