Loss of power at 65 mph to eventual stall

[Duramax66]

Please, I need help, I have a 2000 F-350 ccsb 4x4 that will drive in city conditions fine, but as soon as I have a load or try to maintain a steady speed of 65 mph it loses power and sounds like detonation under the hood ( a sort of clicking or knocking noise). I replaced the in tank screen, fuel pump, filter twice, there was dirt but none of this helped, now the weird thing is if I have 3/4 tank of fuel or less the truck runs perfect for having 200k miles.
I have thought of sensors and injectors, but it doesn't make any sense if the tank is half full and it runs perfect. Completely confused, any help would be appreciated.

Thanks for any advice I may get

[capt.dru]

I had the same problem you are experiencing. It ended up being the fuel sending unit inside the tank. When i took it off the problem went away. I did away with it completely.

[KryPTiC]

almost sounds like your tank is going on a vacuum, maybe try running a full tank with the cap off?