MGS PO is notorious for its stamina drain rates. But luckily, there are few parameters we can tinker with via cheats.
In-game, stamina reduction happens:
- On actions (jump, cqc, etc...)
- Every second when walking, running, crawling, hanging from ledges or dragging bodies
Reduction coefficients are stored at 0x08AFB02C (0x202fb02c in CwCheat notation). In ULUS10202.ini under Hunger Fine-Tuning section are coefficients I was able to find/map with their defaults. Remove lines you do not need to override and adjust the rest.
Experiment!