I had a 1998 F150 4.6L and it did the same thing , all you needed was an oil filter with a built in check valve and that fixed it.
Anyway I have the same knock on my new truck and the only thing I would try would be to go to synthetic oil( Amsoil )see if that changes things and make sure that the filter you get has a check valve - that prevents the oil from draining out of the top end at rest . My next oil is due in July , so I'm going to try and will report my findings then

 

I listened to it this morning, and it does sound like an exhaust leak. When I take it in for an oil change I'll have them look at that, the non-working remote door locks, the elusive rear-end clunk, the trans hiccups, and the stopping hard drive in my RER head unit.

As usual, it'll probably come back as, "we couldn't find anything wrong, everything works fine".

 

Now that you mentioned the trans hiccups, my truck does the same thing too. It has happened maybe 5 times since I got it in March. Also, my doors stopped locking and unlocking from the inside. It only works if I press the unlock button on my remote first.

 

Hey guys new to the forum and im having the same issue on cold starts sounds like a bad lifter or ? anyhow i only have 11000km on it and no that the noise wasnt their for the most part or not that noticebly at first im bringing the truck to the dealer next week to have them listen to it so before i do that i desided to investigate it my self as its driving me nuts. Im an ex motorcycle mechanic so this is what i did.

Started truck first thing in the morning as that is when its the worst( colder temp) then let it warm up to let it idle come down also have the driver window down as i can not here it with it up place truck in drive as the load on the motor makes it sound worse and just feather the throttle lightly and the sound gets worse.

Here is what i found with the hood up and someone in the truck feathering the throttle i was under the hood listening with a stethoscope over each cyl. on top of the rocker covers and found the noise on mine comming from the #1 cylinder its deffenetly a lifter ,pushrod or bad valve guide and seems to be comming from the exhaust vavle anyhow if you guys want to check it out before bringing it to the dealer and maybe getting a line of crap just to see if all of are problems are related to the #1 as binging the problem

Thanks P.S ive also checked other forums and utube and think this is going to be a problem with this engines 5.7 anyway as some people are reporting that thier are engines with bad exhaust valve guides and maybe pushrods that may be to short i no one person said they had the cylinder heads replaced because of to much exhaust valve guide clearance wish adds up as the noise seems more related to the cyl. head then the lifter.