Hello!! My F150 5.6L 3V engine makes a raspy knocking noise

Yes 1clubinside, you are correct. It's a 5.4L (sorry!). It is a ticking sound when I first start the truck and the engine is just idling but, definitely a knocking sound when decelerating my speed down to a stop (right at about 5 to 15 mph). It sounds just like if you were to take a wrench and start banging it on the engine mount. Definitely loud knocking. Which stops as soon as I come to a complete stop and then it just idles (with that ticking sound).

ok,so you have an exhaust manifold leak/crack and it will get worse. as far as the knocking,it's not a rod knocking because that don't quit. it's external somewhere? could be a heat shield,drive shaft or the ceramic cone inside a converter broken loose(had this happen on my F150,sounds like a rod knocking),it could be a number of things. best to get it on a lift to try and see if anything is loose,also get someone(mechanic)to drive it to try and identify the problem if you can't locate it. good luck.