I think I found it. May be an exhaust leak at headers. Looks like one of my header bolts backed all the way out and feel out. Lol. Sounded like a rod bearing or something. I know I got a little rod bearing wearing out cause I've had minimum metal shavings sometimes or its just dirt but I didn't know if the bearing finally just gave.
2004 Mustang GT 5 Speed Full Bolt Ons 385rwhp 450rwtq
2004 Mustang GT 5 Speed
Full Bolt Ons
12.1 @ 117.9 (1.7) in 1/4th
7.6 @ 92.1 (1.6) in 1/8th