Hey Land Rover Girl,
I'll offer my .02 here too. The Air flow meter and lambda sensors being bad probably caused the misfires to happen along with (possibly) the fuel injector code. If I were you, I would start by replacing the Lambda (O2) sensors, then clear the codes, drive it for a bit and have them checked out after a few days to see if any came back. That should help you narrow down the problems.
BTW, how many miles do the current O2 sensors have on them? and how many does the truck have total?