Did they not fix the issues with the 1KZ-T "E" ?
Mines(1KZ-T) done 125,000 Miles roughly and still reliable, but like Crushers has said the first 1KZ-T had a few issues.
But then in the UK here its supposed to be a solid engine, so I am not sure whats "what" anymore...
The 2LT was certainly a problem, but my mates is on 100,000 miles in his LJ70...
I am begining to wonder if these problems dont show up as much over here(UK) for an unknown reason, maybe its all those lovely mountains you have out there? My longest hill around here can be driven in 30 seconds

The only time I have really seen mine overheat is when I plugged the radiator with MUD!!!
I blew my first KZJ70 becuase of the same reason, now I keep my eye on the temp gauage and take the radiator out regulalary to hose down.
Sorry I dont know the answer to Orange Crates question, my guess is the ecu does something funky depending on what gear you are in.
You can probably fool it to think its in gear something, but what that does to the ecu and driveability i dont know...
Maybe you find someone with 3.0 Collorado (90 series) and unplug the gearbox ecu plug, see what happens?
They might be just sensors hopefully?