Simple Checks (Do these first):
* Dirty Air Filter: A clogged air filter restricts airflow, leading to a rough idle and stumble during acceleration. Replace it with a new one. This is the cheapest and easiest fix to try first.
* Low Fuel: Sounds obvious, but a low fuel level can sometimes cause erratic fuel delivery. Fill the tank and see if it improves.
* Faulty Gas Cap: A loose or damaged gas cap can allow air into the fuel system, affecting fuel pressure and causing issues with acceleration. Ensure it's securely tightened and in good condition.
More Involved Issues (Require more investigation):
* Dirty Throttle Body: Buildup on the throttle body can interfere with its smooth operation. Cleaning it with throttle body cleaner (following the instructions carefully) might resolve the problem. You'll likely need to disconnect the battery before doing this.
* Mass Airflow Sensor (MAF) Issues: The MAF sensor measures the amount of air entering the engine. A dirty or faulty MAF sensor can send inaccurate readings, leading to a lean or rich fuel mixture and causing a stumble. Cleaning it (carefully, with MAF sensor cleaner) or replacing it might be necessary.
* Ignition System Problems: Worn spark plugs, faulty ignition wires, or a failing ignition coil can cause misfires, resulting in a rough running engine and acceleration stumble. Inspect these components and replace any that are damaged or worn.
* Fuel System Problems: Clogged fuel filter, low fuel pressure, or a faulty fuel pump can restrict fuel delivery, causing hesitation during acceleration. Checking fuel pressure (requires a fuel pressure gauge) and inspecting/replacing the fuel filter are important steps.
* Vacuum Leaks: Leaks in the vacuum system can disrupt the engine's air/fuel mixture, causing rough running and stumbling. Inspect all vacuum hoses for cracks or damage.
* PCV Valve: A clogged Positive Crankcase Ventilation (PCV) valve can cause excessive crankcase pressure, affecting engine performance and potentially leading to stumbling.
* Throttle Position Sensor (TPS): A faulty TPS sends incorrect signals to the engine control unit (ECU), affecting fuel delivery and ignition timing. A faulty TPS will need to be replaced.
Advanced Diagnostics:
* OBD-II Scan: A scan tool can read diagnostic trouble codes (DTCs) stored in the ECU. These codes can pinpoint the source of the problem. This is a crucial step in diagnosis.
* Professional Mechanic: If the above steps don't solve the problem, it's time to consult a qualified mechanic. They have the tools and expertise to diagnose more complex issues.
Important Note: Safety first! If you're not comfortable working on your car, don't attempt to fix it yourself. A professional mechanic can safely diagnose and repair the issue. Working on the fuel system or electrical components incorrectly can be dangerous.
