Yes, check your timing. Do you know if she had grand kids that she let use the car? Could she have duped you like Barney Fife?
What year is your car, BTW? Is it by any chance a 95? Probably not. It would take an old lady years to put on 68k.
Shouldn't your plugs be gapped at .052-.053? I think there is a difference between AOD and T5 computers as far as timing curves go, so you may want to get a computer out of a T5 equiped stang.
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351W 89 Mustang GT Convertible