Sounds like rebuild time. You could always upgrade to a 4R out of a V6 but that'll require a standalone controller like the US Shift or just get a manual valve body.
2000 Mustang GT Steeda #0048 34k miles. 99 Cobra 4V swapped, FTBR IRS swapped, exhaust, tuned by James Gordon.
Just because I give you advice, doesn't mean I know more than you. Its just means I've done more stupid ****.