wont start sometimes
 

02 f250 powerstroke can start right up or it wont. usually start, then shut it off and wont restart for approx 20 minutes. put a new ignituion switch in didnt help. key works fine all lights on dash work,hear relays clicking. when it starts runs finedoesnt seem like it starter, that is less than yr old. any help would be helpful. thank you in advance for any suggestions