I do not seem to see people having problems with the fusible links coming from the battery.
I have replaced mine three times over the years.
My Monti when two years old did what yours is doing, I tried everything and then did a turbo conversion.
It still lost power climbing a hill!
I then discovered one of the three wires in the fusible link that brings power to the ignition was bad causing a low voltage at the coil. Solved the issue.
If I recall it is the green wire in the link set at the battery.

Cheers, Charlie
If It ain't broke, Modify it!
87 Montero turbo Converted back in Spring1989
95 Montero SR 3.8 DOHC Only one?
93 Pajero 3 door 6G75 Mivec with paddle shifted 5 speed
Then a Gen2 SR with full coil independent suspension.