I seem to have a fuel pressure problem as it takes a few seconds for all cylinders to fire when I start the truck. My questions are:

1. Does the fuel pump hold the pressure in the fuel lines when the truck is not running?
2. When a fuel pump goes bad, can it be gradual thing or does it just stop working?
3. Does the fuel pressure regulator hold the pressure in the fuel rail/lines when the truck is not running?
4. When the truck is not running, can fuel injectors start leaking and therefore causing the loss of fuel pressure?

This is on a '91 6g72 motor.

Any help I'de appreciate.
Thanks.