1987 Ford Mustang Slipping in reverse

Hi there,

Thank you for the donation,

I would say that there may be a sticky valve with in the vale body, this may come good if you get the trans up to normal operating temp with going for a drive, do not over sped the trans, when hot do a service and change the filter, this can often fix sticky valves, if this is not working, a trip to a trans specialist is in order.

Mark (mhpautos)