2000 neon wont start?

have a 2000 plymouth neon wont start it does crank battery has been replaced... i have had 2 people tell me the crank shaft sensor is shot.. i have pulled it out and cleaned it up it spins roughly not sure if it should spin... when i tired to start it sunday it would crank normally for about 3 turns then would be a long crank ... i cranked it today and its just normally cranking but wont turn over.... any idea would be very helpful