I have a 99 f150 I just got the 5.4 rebuilt last year due to a spun rod bearing. Now it has a bad knock on cold starts it lasts for about a min. Unfortunately the shop that rebuilt my motor closed shop so I am screwed on my warrenty. I have less than 10000 miles on the motor. I have looked at alot of post on the subject but really nothing on a new motor just high mileage. So any input here would be appreciated.

 

what filter are you useing?

 

^^Agreed, check the oil filter. If it's a Fram (orange can of death) or cheapo no-name brand, then change it soon.