I know you changed the plugs but i had a "tick" on my truck for the best part of this year and it was driving me crazy.....
Read all the reports about Phasers, lifters and all those other nasty repair jobs but what happened in my case...it was number 4 plug loose.
I changed all the plugs and the motor is very quite and running fine.

 

go out when it is warm and making noise and shut it down.... Unplug the VCT solenoid wire on the valve cover (by the filler cap) and restart....


Do the noise go away? if it did you can do two things... 1 replace the VCT solenoid at 110.00 locally or 70.00 at rock auto...

or 2... try thicker oil...like 10w30

you can actually see the condition of the VCT solenoid if you have access to a scanner. you can see the range of the banks and check. when it is noisy it is usually bleeding oil to the Retard channel so normally you get a lazy running truck slightly but you may not notice this with age.

the range on the VCT solenoid will oscillate from -1.85 to +1.85 or slightly more/less to keep the cam at/near 0 degrees. if you see one dipping more past -2.00 it is bleeding off oil to the Retard channel.

raising the idle will start to show the duty cycle of the VCT where it starts advancing the cams...

I ran into the same issue... you can also pop the VCT seal and swap the solenoids sis to side... if the solenoid is bad the noise will changes sides.

to do that you have to take the power steering reservoir bracket off. I just zip tied the tank to the brake line and removed the bracket to test. you'll need an 18mm socket for the lower bracket bolt... it wont need fully removed as the bracket is notched to fit the bolt....

I am not sure if torque pro will see the values but most scanners like the snap-on unit will.... its how I found my issue. I left the solenoid and swapped to 10w30 oil and the issue went away immediately...

 

Have to pull valve covers on my 2007

 

for vct solenoids?

same solenoid 2004-2007 so you should not have to. pop the seals out and there is only 1 hold down screw which is a torx-30

 

UPDATE: I brought the truck to the dealer on a Thursday and the next morning they fired it up and there was NO tick!!! They drove it all day, parked it out overnight and the temperatures dipped into the 20's, started it up and still no tick! Brought it into the garage and ran all all morning, no tick. I picked it up today and I can't believe how quiet it is ( besides the usual fuel injector noise this truck makes ). The only thing I did about a week before was add a product called Rislone. It may have taken a week of running it before it worked?? You all heard the noise this truck was making, now its quiet. They were going to take the head off to check it, whew!! That was close! It may come back, I don't know, but for now I will enjoy the non-sound of my 5.4

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I tried that and it did not work for me. Glad it did for you.