I just bought a used 2004 jeep wrangler 4 cyl engine it started fine for about 2 weeks and now sometimes it just wont start it just makes a clicking sound and othertimes it will start right up. But when it is just making the clicking sound and i slam my door really really hard, it will start up on the next turn. is there somekind if loose connection i should be looking for? Any help would be appreciated.