denslexusgx470

I have a clean and well-maintained 2003 GX 470 with 171K. All maintenance performed – no leaks, no issues, etc. Recently, it started making a ticking noise when warm. It also had a slight "knock" to the engine as well. I had the lifters adjusted and the PCV was replaced. It's definitely better but not "Lexus-smooth." The mechanic and dealership say it's characteristic of this engine/year. I've read other threads that mention similar issues but nothing specific unless I can't find the thread.  I've noticed that when I press the gas pedal down while idling the knock noise lessens, the engine remains smooth, the ticking seems be less severe as well. Can anyone out there give me some guidance? Thank you!

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Thank you in advance for your time!