When I turn the key to "ON" position fuel pressure
goes to about 42 Psi and then starts dropping
at a rate of about 1 Psi for every 2 minutes.
At idle pressure is 36 Psi and the car starts fine
every time.
Does this sound like a leaking injector ?
Would this explain a litltle rough idle and a loss of power ?

 

Could be. You can pull the fuel rail and pressurize the system to check for a leaky injector. Another thing might be a leaky regulator.

 

What happens to the pressure after the car is shut off? Either leak would cause the pressure to drop really fast and would more than likely cause hard starting.

You didn't mention where you are located or ambient temperature when you checked it. I live in SE Virginia at sea level and my pressure will vary at idle from 51 to 41 pounds depending on what seems like temperature. The higher pressure appears at lower temperatures.

 

The specs are 41-47psi at idle with the vacuum line disconnected. Put the vacuum line back on and rail pressure drops in proportion to intake manifold vacuum.... 36psi on a stock cam is not unusual. When you open the throttle, pressure should rise to the "no vacuum" value, and should hold to that value, within 1 to 2psi all the way to max RPM/max engine load.

There is no "temperature" compensation for fuel pressure, and there is no reason for the fuel pressure to rise to 51psi at any time. That would indicate a defective fuel pressure regulator, or an obstruction in the return line.

Turn the key on, without starting the engine. Pressure should go to 41-47psi, and the pump shuts off. Watch the pressure. Losing a few psi initially isn't unusual, but if it drops to 20psi in a few minutes, its a problem.

Loss of fuel pressure at shutoff could be a leaking check valve in the fuel pump, a leaking diaphragm in the fuel pressure regulator, leaking injectors, or leaking lines.

 

I'll start checking. Thanks guys.