What do you think is the problem

Usually upon reaching temperture the truck will shut off for aprox 1/2 to 3 seconds and then run normally. This has been going on for months. Lately along with the shutdowns it stops running completely. I have to pull over and try to restart which it has reatarted. The fan motor to a/c continues to run so its elect to fuel or fuel related. Also one in 30 starts it is hard to start.
I have changed fuel pmp, fuel filter, coil, ignition switch, ignition tumbler, elect control module, fuel positon module, changed relays, plugs rotor and plug wires with no positive results. I want to change the computer but don't know if that will help.
the truck is a 4.9l manual transmission