Ford 2003 Mustang Workshop Manual page 2583

23. NOTE: When the battery is disconnected and reconnected, some abnormal drive symptoms
may occur while the vehicle relearns its adaptive strategy. The vehicle may need to be driven
16 km (10 miles) or more until the vehicle relearns the strategy.
Connect the battery ground cable.
24. If required, fill the transmission with clean automatic transmission fluid.
25. Check the transmission for correct operation.