Sounds like two issues, one being a bit of wrist pin slop (a small, soft tick/tap sound) and the other (your high speed noise) probably being carbon buildup. The OHV 4.0 is well known for developing a slight wrist pin noise, there is a TSB on it, but it doesn't affect reliability or longevity. Also, in the day, Ford wasn't doing repairs for that noise. There is also a TSB discussing how to remove the carbon buildup. The preferred solvent for doing this in a thorough and complete manner is PM-3, available at your Ford dealer. When done implementing the TSB, remember to change out the now dirty plugs, oil and filter.
I don't like hearing this, "Now when I accelerate and let off at a high rpm it knocks terribly.". is this at idle or when driving? Is this a different knock?