With a good rebuild and 5.29 gears, you should be fine. I would surely check the following:

Fuel pump - make sure it is good and pumping proper vol.
Wiring harness for the injectors (known 22RE problem)
Fuel filter - clean?
Air filter - clean?
Distributor - is this a known good part?
Coil & Ignitor - again, known good parts? Nothing loose?
ECM - known good part?
Vaccum lines - assuming it idles and accelerates properly?

The part about the engine just quiting is the trouble for me. These motors are not real high on HP to begin with, but they are fairly toquey. You may not get the job done the fastest with a 22RE, but you will almost always at least get the job done. These are great little motors, just not fast. However, they should not just die. I would be thinking along the lines of some sort of fuel loss or spark loss. Going up hill in 4x4, was it a real bumpy trail? If so, you may just have a loose wire or short somewhere...

Tell us more and keep us informed, the more info the better....

Thanks,
James