Help on my 440 Duster

Ok when I go and try and start it it will only turn over a few times while the car is in park then will not do anything nothing turn the key nothing then I have to put the car in N and it will again crank over ok just to explain this hard starting is a problem as of late and when I get the car started it runs as good has it always has just when I shut the car off it goes back to being a ***** to start . I have found that if I snap the key back to run it will fire faster then if I keep trying to crank it . The battery is fine .