Preventative Maintenance

The Toyota software will allow you to observe the flow rates of your EGR system cooler etc so just keep an eye on that and as things start to close up and flow is reduced then it's probably time to clean the intake manifold the EGR cooler and it's related ways and valleys sure you could rip it all apart right now but if it's not clogging up and the numbers aren't getting anywhere down then what for You want to keep the thing running fantastic like it is now more than likely not start ripping it apart especially with limited garage space I try to do that stuff in the spring and or the fall when it's nice weather out here where I live it's not 110° or even in the early part of the winter when it starts because then it's reasonable down here like in the '50s you can stand outside work for an hour or two without getting uncomfortable.

 

You may need to hunt to find a shop to do the OCC, just because it is custom work.

If it were me I'd do the EGR/intake work now, the plugs & coolant work in a year (that's 15-20k for us) and the water pump never unless the old one broke first.

So many random things happen with used cars. Compressing a big list of work into something you call "preventative" is just putting all your eggs in one basket. If something big you didn't notice blows out in June, you'll need some cash on hand to deal with it. Better to have the savings standing by (or earning interest) when dealing with 10+ year old cars.

Another example: your car gets in a crash and insurance decides to total it, which doesn't take as much as it used to because body shop labor is going up while the value of the car has dropped from age.

Without some heroic hounding of the adjuster, you're going to get the same reimbursement check whether you've neglected the car since purchase or spent a fortune on recent maintenance. When you consider that risk, it may make more sense to split up the repairs and pay as you go.

 

If there are no symptoms, nearly everything on your list can probably safely wait. I'd maybe clean out the manifold passages, and do the easy check of EGR flow restriction via OBD2.