I have a 2001 mustang. aod tranny. about a week ago it started slipping really bad. we got a new filter and changed out the fluid and it was fine. then yesterday first gear started acting up. no reverse problems at all. I've just been doing 2nd gear take offs and that was working fine but now it won't shift into 3rd. when we changed the filter we forgot the new gasket. if we change out the fluid again and put a new gasket on will this fix the problem?? at least temporarily?

 

Pull the dipstick out and smell the fluid, if it smells burnt, that tranny is toast.

Ops, you just changed the fluid, was the old fluid very dark and burnt smelling?

Honestly, it doesn't sound good for that tranny, when they start slipping, that's usually the end.

But welcome to the forum, wish I had better news.