If you’re doing 3-4 mph up a substantial grade in 4HI you’re asking for a transmission overheat with these high stall torque converters. Regardless, Toyota needs to address the issue. This guy is rationale and the dismissive nature of Toyota is not reassuring.
offroads and likes to use MTS loose gravel, but still has the front lip attached. Hes probably driving around dirt roads at 5mph in 90* heat when he should be using 2hi or just regular 4hi