Time to replace the knock sensors and wiring harness. What else should be done or replaced while the intake is off? I'm also way over due for a timing belt and associated parts. Would it save any labor to do that at the same time?

I would recommend doing all the things from the list below when you are in there.

Valve Cover Gaskets
All Vacuum Lines
Spark Plugs
Spark Plug Wires
Spark Plug Boots
Coolant Flush
Throttle Body/IAC clean

Replace crappy wire loom with HeatProof Tape.

all of the above already mentioned +

-PCV valve, hose and grommet
-intake plenum gasket
-LCE engineering O shaped throttle body gasket, TRD O-shaped, or new OEM D shaped (either, doesnt matter, these 3 are quality, and the LCE may be best).
-Don't forget a new IAC gasket if you clean the IAC. might as well go new if you're already at it

Also, doing your timing belt and associated parts is a separate job, and doesn't require intake removal. It will not save you any labor.

If you have leaky valve covers, this is certainly the best time to knock those out too. Intake must come off, and it'll save you some labor.

Valve cover gasket for sure (intake HAS to come off), and the other stuff mentioned on top already.

Well it looks like I have quite a project. Thanks guys.

Good luck to you! I battled a knock sensor gremlin for months, see my old thread for details. My advice: confirm continuity every way you can before installation, and use Denso products. Many people (including myself) have used the older Matsu style sensors only to experience P0325/P0330 promptly after - even putting out MUCH sloppier waveforms when hooked up to an oscope. I suspect the major difference in quality is why Toyota themselves made the switch
Pretty much everything that can be knocked out at the same time has already been listed above, and is practically everything I did during my debacle. It's really not as much work as it sounds, nearly all of what's listed is dead easy if just a little tedious
I personally recommend the Teflon O-shaped "heat-sinking" gasket from LCE. I spoke with their customer service on it's durability, and the guy I spoke with told me he's personally re-used his 5 times and it still seals great. As for other gaskets, I recommend buying them online - not sure about your area, but stores around me charge like $160 for the plenum/manifold set, but online it's like $40. Absolutely absurd

Definitely all the above. But that makes for one heck of a day. Or two. Lol.

Is there a list of vacuum hoses? Sounds like I should do this to with my valve cover gaskets

You have to remove the fuel rail. I replaced the banjo bolt washers (PN 90430120260) to make sure they sealed well. I also replaced the little o-ring for the Fuel Pressure regulator since I removed that as part of removing the fuel rail. I had some spare injector o-rings as well.

I’ll second the IAC gasket comments (I used OEM) and I used Fel Pro MS 95898 plenum and manifold gaskets which are fine.

I rewrapped my engine harness too since the plastic was crumbling to bits. I used some sort of silicone tape and it’s been holding up.

I also recommend this gasket. I use it with no issues, high quality piece that removes the "D" Shaped gasket at a cheaper price than a TRD O-shaped one