V8 Help engine loses power whe going uphill

Good Day all

I am a proud owner of an 1985 land rover 90 V8 3.9i from Jordan

my problem started few months ago . when I’m going uphill the car loses power and start making noises like there is shortage of fuel and when the street is flat again it restores power

I changed 2 fuel pumps - spark plugs - spark leads - fuel filter - air filter - cleaned fuel injectors - cleaned fuel tank - changed distributor cap and nothing happened .

is it possible that i have a problem with my dizzy ?

so please can anybody help ??

Does it do it all the time with differents amounts of fuel in the tank or when the tank is at a specific level, could be the stack pipe in the tank pin holed

i does it with different amount of fuel
forget to mention i changed all fuel lines also