Ok got

4.6 about 125,000 runs very good manual trans 4x4 been decently maintained anyway once motor warms I get this knock exspecially if say im in 4th gear low rpm and try to accelerate thats when it knocks worst loudest ok then if I dwn shift and get the rpm up it goes away also if its knocking and I ease off the throttle it will go away plz anyone have any idea what in the hell is going on its making me insane wondering if im about to be shoping for an engine

 

is it a misfire...

 

Spark knock? Try premium gas, if it gets better or goes away that's what it is.

 

They usually knock when #4 starts missing. Can sound pretty bad lol. Doesn't have to be #4, but it's usually the loudest.

 

#4 missing as in a timing issue or plugs wire etc.
Or r ya saying im losing that cylinder ? I got the truck last summer from a private owner and it is overdue for plugs wires and all that btw on the octane post I plan on putting an octane boost in this aft ....well thanx for the advice guys ill update hopefully its a simple fix....hopefully

 

Not sure bout the misfire either im planning on looking into any lead that dosnt involve a engine puller lol I was thinking an exhast leak but strange that it will not do it when cold only once motor is up to temp

 

I'd replace the coils if you haven't done so yet (They're affordable online). Wires as well. Also, make sure your using either Motorcraft, NGK or Denso plugs. Something these modulars like.

Keep in mind, the wrong PCV valve (motorcraft only) can mimic engine knocking. Since aftermarket and 3rd party supplier replacements don't contain the correct margins.

 

I had a knock once that turnedout to be my air conditioner compressor.
would have sworn it was the engine.