There would have to be a vacuum at the pressure regulator. If the MAP sensor goes bad, the ECM can't accurately calculate engine load, which means the air-fuel ratio will become either too rich (more fuel) or too lean (less fuel). ... This leads to excessive fuel consumption, poor fuel economy, and possibly detonation.
If the sensor is disconnected, the fuel load will be excessive. Makes me wonder what was going on when the engine just quit when you unplugged the harness. I could see it choking down from flooding, but not just stopping as if the ignition was turned off.