Yeah, at 184k, if I'm suppose to change my fuel filter, I'm way overdue. You're not going to go more than a 265 tire on this truck so no gear change is needed. I've always changed my own oil. Mobile 1 and Baldwin filters. Doesn't burn a drop. And stock up on the oil drain gaskets. Don't reuse the old one. I go every 8k miles between changes. I'm sure I could go longer. I run Chevron Techron fuel system cleaner every oil change now. Not sure if I'm doing any harm or good. I change the air filter when it looks fairly dirty. I've cleaned the PCV valve a few times with carb cleaner and the MAF with CRC MAF cleaner. Spark plugs every 30k as per the schedule with the NGKs or Densos originally installed. I wonder if Toyota still puts NGK on one side and Denso on the other? Folks used scratch their heads over this one. Maybe they were just trying to tell owners either is okay. And anti-seize on the threads. The proper anti-seize.
At 100k, I changed the serpentine belt (old one looked fine). Not that I let that deter me. Also, the thermostat and a coolant flush. The 4.0L has those nice little drain spigots on the block under the exhaust manifolds. Very handy. You only need to open one side. The passenger side is easiest. I was going to change the radiator hoses but the Toyota parts counter guy I've known for years said they are good for life. They still look and feel good so, I've never changed them. I plan on redoing this at 200k. I'm thinking I might change the tie-rod ends at 200k. A broken tie-rod end can really ruin your day.
Grease the u-joints in the spring and fall. And I change the brake fluid when it looks dirty. The dealership changed the power steering fluid once, recently. At least they said they did. The color of it didn't lighten though, so I have my reservations.
Mods I'm happy with: A scan-gauge, OME suspension, ARB front bumper. Second battery set up as a backup, not an accessory battery. Saved my bacon twice now. Weathertech floor mats are like new after ten years. TRD seat covers are just as old. Some wear but well worth it. I switched them side to side awhile back.
I put Amsoil fluids in the diffs and transfer case a long time ago. It's suppose to be good for 250k miles. We'll see.
From day one, anything I did had to keep the truck comfortable for long cruises. That was always my main concern.
There are no performance mods worth a tenth of their cost.