So this is a long shot I had a lifter knock on my 4.0 it’s a 2001, so replaced lifters, pushrods, rockerarms, springs changed the oil (no metal flakes) and I have perfect oil pressure but yet it’ll run for 10-20 minutes fine then knock. Once you let it cool down it’ll run great but it’s persistent and never changes I don’t know if it’s a oil pump or fuel related but it’s super confusing maybe someone had this issue before. The motor has 180,000 on it

 

what oil are you running ? and maybe a video would help if we can hear the knock .

 

If you're talking about lifter rattle, that's normal for a 4.0 and they will run forever that way, unless it's something like a cracked piston skirt, I wouldn't be too concerned.

 

Isolate the knock using a mechanic's stethoscope.

 

I’m running 10-30 I have been for awhile now but it was super clean I’ll take a video of it but it’s at my buddy’s shop right now