[Shaggy]

Okay let start with the basics if it is not running have you check for spark all the way to the plugs amd fuel all the way to through the injector?

The other thing might be a faulty ign. switch check the coil for voltage. Hook a meter up to the pos and neg coil wires have a buddy get in the car turn the key on and see if you get voltage . Then have him start the cat and see if you get voltage then and finally see if you still have voltage once he releases the key back to the run position.