Car is a 2002 Legacy Outback with a 2.5L four. Manifold-pressure based injection, not a MAF. Ran fine until yesterday when it started up, revved to high idle, then stalled after a few seconds. It can be kept running for a while by pumping the gas, but always runs choppily and stalls in the end after 10-15 seconds. Restarts immediately, starts smoothly, then starts cutting out.

The immediate restarting makes me think it's not the fuel pump or filter, and the fact that it stalls even when pressing the gas makes me think it's not the idle motor.

Timing belt was done 10,000 miles ago, so I don't think it has jumped time either. Betting on an electronic problem, maybe a sensor. Ideas? I don't have the repair manual for that car, and it's not actually my car, but if I can sort it tomorrow, I'd be appreciated

EDIT: looks like disconnecting the manifold pressure sensor allows the car to run/idle in limp mode. Guess I should swap the MAP sensor tomorrow and call it a day?