Does this happen only after the truck has been running for a lengthy period of time?
If so the coil is likely the first suspect. When they leak their coolant they overheat causing with bad starting or running as you are seeing.
Next up, the fuel pump my be close to the end of its life.
A friend of mine runs a land rover / range rover specialty repair shop. Based on his experience, they are capable of stopping anywhere, anytime, at any cost.
I don't know about the brakes, only their unreliability.