My top ten recommendations:
1. Replace and preferably re-route the fuel return rubber hose which is invisible behind the fuel injection pump, before it fails totally in the middle of the Everglades while towing a travel trailer, on vacation with the DW. You need fire extinguishers handy.
2. Get JoeG to send you his fuel system email attachment and follow his advice concerning fuel system overhaul, including trashing the fuel heater before it catches fire. Definitely have the fire extinguishers on hand. The cab will fill with smoke if it ignites. No need to check diagnostic codes!
3. Clean the fuel solenoid and fit a new rubber boot, before it sticks and stops the fuel flowing in a dark parking lot at 30 degrees below.
4. Make sure the KDP (killer dowel pin) fix has been done, rather than seriously smash the front end of the engine at a cost of thousands of dollars.
5. Clean the TPS (throttle position sensor) so that torque converter lock-up is stable. I find removing and dismantling the best way to do this.
6. Change the brake fluid. Pressure bleeding using a spare tire is good.
7. Change all the coolant hoses, including all the small ones, like the thermostat bypass hose and the ones on the line to the trasnsmission fluid heat exchanger and the cab heater. There are a lot of them.
8 . Fit heavy duty contacts in the starter before it fails, as it will if it hasn't been modified. LarryB has them. Also check the insulators where the live battery cable attaches to the starter. I was lying under the truck tryin to work out why the starter was causing a problem. I waggled the cable, it arced, and a fire started in the oil and grease on the engine, and the dry grass caught fire around my head and shoulders. I called to the DW "Get the fire extinguisher from the trailer". I heard noises, and then the reply, " It seems to be stuck in its bracket. It's a good job there isn't a fire. " My reply : "There is a fire. "
I think we can laugh about it now.
9. Check for broken springs on the front of the A/C compressor clutch, before damage is caused to the rest of the clutch.
10. Overhaul the alternator before it fails. A simple piece of preventative maintenance with the right kit of parts. (Fostertrucks, aka Larry B)
These would be a good start, if you haven't already done them. Don't ask me how I know about the importance of these items
Nick