Weird engine noise at low RPM

[Lc'S'08]

So, I took our 2008 expo EL with 103k across country from california to New York. I found in some northern mid west states there's only 85 octane and so I bit the bullet and filled up because I was needing gas. While driving up Mount Rushmores iron mountain road I came to a stop at the first tunnel to see the monument and when I tapped the gas to go there was this metal grinding terrible noise. It wouldn't stop unless the rpm was over 2,000 and was very prominent in the 1k-1,500 rpm range. I've read and heard about the cam phasers and solenoids, so I unplugged both solenoids and the noise still there. I've also noticed that after switching to Mobil1 synthetic 5w20 at full operating temp there tends to be more valve train noise after coming to idle from a freeway stretch or other more than a few mile trip when it's hot out. An old mechanic suggested changing oil to 10w30 or even a 10w40 to see if the thicker oil would provide higher oil pressure at idle from driving a good stretch. I bought cam solenoids but realized that the '07 and up don't allow you to change the solenoid without removing the valve covers.
Has anyone else experience excess valve train engine noise in this mileage range and what oil have you used or switched to. I had ran motorcraft oil up to 100k then decided to go synthetic and now maybe because of the heat outside and the viscosity of synthetic @5w20 may be the cause for more noise but I'm not sure. Everything else runs fine. No loss of power, no codes, no leaks and plugs changed out without breaking any at 90k. Any advice comments or other technical know how would be greatly appreciated.

 

[Jdm5630]

I also have the same symtomps you are having. Mine sounds lick a soft ticking noise at idle. Where are the solenoids? I want to try and disconnect mine to see if the noise stops.

 

[Lc'S'08]

Solenoid location

The solenoids are at the front of the valve covers. One on each valve cover. They look like a plug coming thru a grommet type opening. Get the engine hot and while it's running unplug both and raise your RPMs up between 1-1,500 area and see if the noise is still there. You may trigger the CEL but after you plug them back in it'll go away once the computer cycles thru. Maybe a few miles of driving.