1. Check the fuel filter: A clogged fuel filter can restrict fuel flow to the engine, causing it to run rough and hard to start. Replace the fuel filter if it is dirty or clogged.
2. Check the spark plugs: Worn-out or fouled spark plugs can cause the engine to run rough and misfire. Inspect the spark plugs and replace them if they are worn or damaged.
3. Check the ignition wires: Damaged or loose ignition wires can cause the engine to run rough and misfire. Inspect the ignition wires and replace them if they are damaged or loose.
4. Check the distributor cap and rotor: A faulty distributor cap or rotor can cause the engine to run rough and misfire. Inspect the distributor cap and rotor and replace them if they are damaged or worn.
5. Check the throttle body: A dirty throttle body can cause the engine to idle rough and stall. Clean the throttle body with a throttle body cleaner.
6. Check the intake manifold gasket: A leaking intake manifold gasket can cause the engine to run rough and idle poorly. Inspect the intake manifold gasket for leaks and replace it if necessary.
7. Check the fuel pressure: Low fuel pressure can cause the engine to run rough and hard to start. Check the fuel pressure and compare it to the manufacturer's specifications. If the fuel pressure is low, replace the fuel pump.
8. Check the oxygen sensor: A faulty oxygen sensor can cause the engine to run rich or lean, which can lead to rough running and poor idle quality. Inspect the oxygen sensor and replace it if it is damaged or worn.
9. Check the fuel injectors: Clogged or faulty fuel injectors can cause the engine to run rough and misfire. Test the fuel injectors and replace them if they are faulty.
10. Have the engine scanned for diagnostic trouble codes: Your vehicle's on-board diagnostics (OBD) system may have stored diagnostic trouble codes (DTCs) that can help you identify the source of the problem. Have the engine scanned for DTCs and research their meanings to get more information about the issue.
If you are unable to diagnose and fix the problem yourself, it is recommended to take your vehicle to a qualified mechanic for further inspection and repair.
