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So the engine cranks strong just will not start? Is the theft light flahsing rapidly when this happens? If you hold your foot on the gas will the engine start and run? Which engine is in your Taurus? DOHC or OHV?
If it's cranking weak I suspect a bad battery. It may be weak or has a bad cell. As far as the extended cranking it may be a sticking idle air control valve or possibly a fuel pump. You can try tapping on the valve which sometimes will free it up.