The issues you are experiencing with your Pajero IO, such as the engine turning off when shifting into reverse or when pressing the brake/slowing down, could be related to several potential problems. Here are a few possible causes:

1. **Idle Air Control Valve (IACV) Malfunction:** The IACV is responsible for controlling the engine idle speed. If it malfunctions, it can cause the engine to stall when shifting into reverse or when slowing down.

2. **Faulty Brake System:** If there is a problem with the brake system, such as a malfunctioning brake booster or a vacuum leak, it could cause the engine to stall when the brakes are applied.

3. **Transmission Issues:** Problems with the transmission, such as a faulty torque converter or transmission fluid issues, could also lead to stalling when shifting into reverse.

4. **Throttle Body or Throttle Position Sensor (TPS) Malfunction:** If the throttle body is dirty or the TPS is faulty, it could affect the engine's ability to maintain idle speed, causing stalling in certain situations.

It is recommended to have a qualified mechanic inspect and diagnose the specific cause of the stalling issues with your Pajero IO to determine the exact problem and recommend the appropriate repairs.