No battery is new cables are clean ground is good it just happened yesterday first time. When I try to start it and give it gas it still doesn't start going to try it again after some coffee going to see if fuel pump is working
Are you able to remove the starter yourself, meaning do you have the tools to remove it, then take it to a good automotive parts store so they can "bench test" it?
What's confusing is that you first state the starter was good, then you stated it failed. This is throwing folks off in trying to help, as it becomes difficult to trust if other tests you've done are correct.
A best option at this point would be to tow the Mustang to a shop to get a proper diagnoses and repair.