98 Ford Mustang will turn over but won't start.

You don't , you need the dealer or mobile lock smith program new key's .

Start with a scan,then follow factory Ford fault tracing data.....

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Try shooting some starting fluid in air cleaner housing. If car starts, then shuts off after burning off starting fluid then you more than likely need a new fuel pump. But also be sure to check fuel pump fuse and relay. Hope this helps

check crank sensor

turn the knob for the headlights all the way to the left and then the right. it's also a dimmer for the dash lights.

check fuses for brake shift solenoid. the brake pedal position switch is a fuse under the hood. inside the passenger compartment, check every fuse. that's a start for not having more information.

This is from the Ford manual:

When the ignition is turned to RUN or START, the

theft indicator will light for 3 seconds and then go

out. If the theft indicator stays on for an extended

period of time or flashes rapidly, have the system

serviced by your dealership or a qualified technician.

You can view additonal information at this Free Ford website, by viewing the owners manual.

https://www.fleet.ford.com/maintenance/owners_manuals/default.asp

you need to have the key reprogrammed by a locksmith or the dealership. it will only start and stay running with the original or reprogrammed key.

fuel pump, regulator and filter need replacement.

sounds like ecm lost signal from key