Transmission ATF is good, Brakes are good, Tcase has new ATF is good, gas is regular Shell bronze (87), driving style is not aggressive but not Grandma Sunday either.
Been doing a bunch of reading, couple of ideas:
- The O2 sensor(s), likely original and the truck has 185,000 on it. Where is the sensor located, how many are there, are they all the same #, cost each?
- Viscous fan clutch, quite certain it is operating properly. I will pay some close attention to it so see that it is engaging and disengaging appropriately so is not hogging power/economy
- Engine temperature. The gauge is steady, runs at about 1/3rd of gauge. No number indicates. In my experience, warmer runs better, cleaner, and leaner improved mileage. Am looking into higher temperature thermostat options (if any)
Any specific guidance on the O2 sensor would be helpful.
I will update periodically with results as I try a few things noted.