1995 Mustang won't start

1995 V6 Automatic Mustang - Got in my car on Christmas Eve and it would not start, it just cranks. When you crank or turn the key to the on position, the RPM gauge goes crazy jolting back and forth and there is a loud clicking noise coming from the Powertrain Control Module. I replaced the PCM with no luck and also replace the Engine Control Module (ECM). The alternator checks out fine. What is causing this clicking noise coming from the PCM and why are the RPMs going crazy? Thanks for any help

Checked the battery? Most of the time if a car just clicks wont start its the battery.

Yes, I have check the battery and it works fine along with all the interior and exterior lights

I have had batteries test good that were no good. Try putting it in another car and see what happens. Also you could try to starter solenoid.