Engine ticking under load
 

I have a 2008 F150 5.4L and after pulling my trailer I have a really noticeable ticking coming from the engine. When you start it up it is really noticeable for a few seconds then disappears and sounds perfect, once you start to put the engine under load when driving it is really loud coming from the passenger side. Any ideas. ready to scream.

Could be the cam phaser tick. Does it sound like a diesel?
Could also be a bad injector, as they make an audible tick also.
Are you sure it's not the metallic "ping" which is predetonation?

I get what may be the same sound when I start the engine. It too goes away after a short time. Reminds me of my (some day to be reborn) '68 MGB.
In that car the poor design ensured that oil drained away from the rocker arms, pushrods and tappets (lifters) when the car was turned off. When you start the car they run with little oil so they sound loud until the oil gets pushed to them from below.

Unlikely, but a hole in the exhaust manifold? That makesa tapping/ticking sound as one cylinder shoots its exhaust out. I was driving a school's "mini-bus" with a soccer team and I heard a bad sound like that. After 5 minutes a spark plug blew itself out of the head; found it hanging by its wire.

Maybe try an engine oil additive or an oil change. Predetonation or pre-ignition can be from funky fuel or the ignition being off. Looking at spark plugs can tell you if the fuel is burning correctly. There should be a small amount of a light grey or brown deposit on them. Sometimes they have black crud built up or they look glazed. That would mean something is wrong.

Sounds like an exhaust leak to me