Most likely its the inertia switch, it cuts off power to the fuel pump when an impact occurs so the engine shuts off. It should be located in the passenger side footwell according to a quick search. It may be in plain sight or behind the kick panel so be prepared to pull panels out if its not in plain sight.
07 Gt Tungsten Grey
Roush (Airaid) Cai, GT500 Tb with BlowByRacing Adaptor Plate, UPR O/r X Pipe, M80's, Pypes Muffler Delete Axle Back, Sr Performance Adjustable Motor Mounts and Steeda Tri Ax Short Throw Shifter
02 Gt Mineral Grey
Steeda Sport Springs, 3.73s, Pro5.0 Short Shifter, Pypes O/r X Pipe, full 2.5 inch exhaust with M80's, 75mm Tb and C&L Plenum
87 Mercury Grand Marquis