Possible reasons:
1. Throttle Position Sensor (TPS):
* A faulty or dirty TPS may send an incorrect signal to the ECU, resulting in incorrect engine speed adjustment.
2. Mass air flow (MAF) sensor:
* Incorrect MAF readings can result in incorrect air-fuel ratio, causing loss of RPM and stalling of the engine.
3. Idle Air Control Valve (IAC):
*A faulty or clogged IAC valve can cause a rough idle or stalling engine.
4. Malfunctions in the fuel system:
* A clogged fuel filter or fuel pump can restrict fuel flow, causing loss of power and stalling of the engine.
5. Problems with electronics:
* A break in the wiring or a faulty ECU can cause the engine management system to malfunction and cause the engine to stall.
6. Mechanical problems:
* A worn or broken timing chain can disrupt the timing of the ignition or intake/exhaust valves.
Diagnosis and elimination:
1. Check TPS and MAF sensors: Use an OBD-II scanner or multimeter to check the sensor readings.
2. Clean or replace IAC: Clean the IAC with carburetor cleaner. If this does not solve the problem, replace the valve.
3. Check the fuel system: Replace the fuel filter and check the fuel rail pressure.
4. Check Electronics: Check wiring and connectors, and scan the ECU for trouble codes.
5. Check for mechanical problems: Check the timing chain and consult a qualified mechanic.