will turn over but not start on 1999 Lincoln Town Car

batery goes dead over night,replaced rear suspension air bags and fuelpump.had batery and alternator checked. What could it be.

Asked by for the 1999 Lincoln Town Car
You could have a faulty battery. But if you verified the battery holds a load and is fully charged, then you need to check for a parasitic draw, such as one you may have when a relay stays engaged (fuel pump relay, PCM relay, compressor relay for the suspension relay. etc...)

Something may be staying powered at all times, running the computer down.