Is this sound rod knock or something else? How can I diagnose this further?

1999 Ford E-150 5.4

Pulled codes for engine misfires in cylinder #1 & #4. Had an intake manifold gasket that failed and was leaking coolant down into cylinder #1 and near the front of the intake manifold so I replaced it. I also replaced the valve cover gaskets, EGR tube, all of the spark plugs, and changed the oil/filter. After starting the van I immediately heard a loud metallic knocking sound. The sound is constant and increases in frequency with rpm increase. I'm afraid to run this car for very long to see if it might go away. It "sounds" like a rod knock but is there anything I can do to further diagnose what's actually causing this?

I took off the drive belt and the sound remains.

I removed the ignition coils to cylinders 1 & 4 (haven't tested the others yet as they are a little hard to reach) but there was no change. Here is an example of the sound…

https://clyp.it/4uraeltc

Take the valve covers back off and look for anywhere that looks like moving parts are hitting it. I'm willing to bet a lobe of the camshaft could be hitting something there.

That doesn't sound like a rod knock.

Loose flywheel?

You can get a mechanic stethoscope, or use a long screwdriver with the handle to your ear to pin point the sound.

Sounds more like a Camshaft phaser noise… Common issue on those 5.4 3V engines. More often occurs on passenger side of engine… See video link for repair process. May be clogged oil passages in the phaser system… Or weak pressure after changing oil/filter… Maybe run it a while to buildup oil pressure and see if it goes away.

Related info…
http://www.enginebuildermag.com/2009/06/complaints-of-ticking-andor-knocking-noises-from-ford-4-6l5-4l-3v-engines/

http://autorepair.about.com/