i have a 1995 lincoln ,the engins will start but shuts down after about 3 seconds why

Fuel pump problem, or the fuel pump relay is tripped, that is usually behind or near the passenger side kicik panel

Another possible problem could be a clogged catalytic converter. That can also cause the symptoms you car has.

if your fuel pump quits or trips a fuse the car will not start at all so rule that out. There are so many things that could cause this problem you really need to have it put on a machine to diagnosis it. The cars have lots of sensors it could be any number of them bad or the engines computer could be bad the machine will find this for you.

Plugged fuel filter.

Reset the inertia switch in the trunk. Little black box with a white button sticking out.