This one is baffling me so I'll try to describe it clearly. We have a single-spout, single-handle kitchen faucet.
The hot water pressure is just north of a trickle, but only just. The cold water pressure is fine. The faucet itself is tough to disassemble, so to test, I swapped the inlet hoses from hot on the left to hot on the right, same with cold. In this opposite configuration, the water pressures ON BOTH sides are strong and fine. Water gets hot quickly as expected.
Swapping back to the appropriate configuration of hot on the left cold on the right results in hot water trickling while cold water is strong.
What can be wrong or what can I test?