Why does my car smell like gas when I start it.

That's not much information to go on. Is it top secret? Why did you have to "get it running again"? How long was it sitting and why? How did you determine the need to replace the spark plugs and how did the old ones look? How old were they? Where are you smelling the fuel, at the tail pipe, under the hood, or inside the car? Have you checked for diagnostic fault codes? Do you continue to smell the fuel after the engine is running? How does the engine run?

As an update to this post, there are a couple of things to be aware of for these early Intrepid / Concorde / LHS models. This service bulletin addresses fuel leaks from the fuel rail and injector O-rings. You might smell gas under the hood, but much more commonly you'd smell it inside the car when the heater fan was running.