OK, I am new here, so going to test the waters. I have been a Ford owner since the mid 80's. I just bought a 2012 F250 SD, 6.2L.

I bought it knowing it had misfire issues, so it was a decent price.

Here is the list of codes is has: P0019, P0017, P0300, P0304, PP0306, P0128, P0307, P0308
It also makes a terrible noise on start up, and goes away after a few seconds. But a random clicking/popping noise contiues.
So after a bunch of research, I tore the valve covers off, to make sure it wasnt a broken spring, but they all visually check out.
I ran a compression test:

4-130 8-110
3-90 7-100
2-157 6-120
1-118 5-100

On cylinders 3 and 5 I added oil and tried the the comp test again, getting 110 and 120 lbs respectively...is the extra 20 psi enough to say its the rings?
I have read that crappy valve timing can obviously cause low compression.
I have also read that that terrible noise on start up can be caused they the hydraulic tensioners taking a bit to do their job, maybe just gaskets?
I am going to do a leak down test on the cylinder so see what I can get out of that.
My thoughts, change both Phasers, VVT actuators, chains, tensioners and guides, and oil pump.
Should I be worried about the low compression?? It doesnt burn oil or anything. Maybe the leakdown test will give me more info.

 

I think you are on the right path. Valve timing has a direct impact on your C/R.

I would inspect and repair the valve timing equipment then retest the C/R.