While your injectors might have been going out, I suspect the HPOP fittings were the real reason for your trouble. To keep your new injectors running well, use a cetane additive that adds lubricity to today's low sulfur fuel.
I suggest having a Scan Gauge 2 or other device to monitor the vitals on your engine. I would monitor the following: FICM output voltage, HPOP pressure, Coolant temperature, Oil temperature. There are number of these $150-200 monitors that simply plug into the diagnostic port of the truck and do not alter your OEM programming or wiring.