2006 Dodge Magnum Car has problems starting.

I have this 2006 magnum and everytime I go to start the car in the morning or if its been sitting for a about 8 hours it starts but it act like i starts and cuts off and then starts. I have to turn the key all the way to the right and wait until the car has started. normally you would hold the key to the right and immediately let go. After the car has started and I cut the car off and go to start it after I get out of a store I never have this problem. Its only when the car has been sitting for hours. I recently got a tune up with spark plugs and it still does the same thing when I start the car. If i start the car and let the key go right away the engine shakes and then works its way up to starting.