Please Help!!!

I had new injectors put in my car. Right afterward it has been hard to start. I was told one of the new injectors may be leaking. I ran the engine, shut it off and took out 3 spark plugs(front). I heard a hissing sound through the plug hole of one cylinder and not the other. After a while the hissing goes away. If I turn the key so the pump runs but not the engine, then turn the key to OFF, the hissing sound becomes louder and after a while goes away. The hissing sound is coming from the cylinder I suspected to be the leaking injector and there is a really strong gas smell coming from this plug hole and not the others. There are no exterior fuel leaks. Could this mean that this NEW injector's nozzle is leaking?
Also the car is only hard to start if it has sat for 5 or more minutes. and no fuel is leaking from the regulator so I assume it is okay?

ANY help is appreciated!!!

It sounds like you have a leaking injector. Since your fuel system gets pressurized when you turn the fuel pump on, it is pushing that pressure against the leak and spraying gas (thus the sound / smell), but after it's off, given enough time, the pressure in your fuel system decreases (and it doesn't spray anymore)

The reason it's hard to start after sitting for 5 or more minutes is because it's been flooded by the leaking fuel injector.

So I would say it sounds like a leaking fuel injector

So, I took the injectors out to find the leaking one. I was shocked to find ALL my new Borg Warner injectors leaking fuel through the nozzles. Any one thinking of using Borg Warner dont waste your time and money.

Thank God for warranties!