1. Fuel System Problems:
* Fuel Injectors: Clogged or leaking fuel injectors are a prime suspect. They can cause a rich fuel mixture (leading to the gas smell and rough idle), hesitation, and erratic idling. A fuel injector cleaning or replacement might be necessary.
* Fuel Pressure Regulator: A faulty fuel pressure regulator can deliver too much fuel to the engine. This would also result in a rich mixture and the symptoms you describe. Testing fuel pressure is crucial here.
* Fuel Pump: While less likely if the car starts and runs, a weak fuel pump could intermittently deliver insufficient fuel, causing hesitation.
2. Air/Fuel Mixture Problems (Beyond Injectors):
* Mass Airflow Sensor (MAF) Sensor: The MAF sensor measures the air entering the engine. A faulty MAF sensor can send incorrect readings to the computer, leading to an incorrect fuel mixture. Cleaning or replacing it is worth considering.
* Oxygen Sensor (O2 Sensor): The O2 sensor monitors the exhaust gases and helps the computer adjust the fuel mixture. A bad O2 sensor can cause a rich or lean condition, leading to your symptoms.
* Vacuum Leaks: Leaks in the vacuum system can disrupt the air/fuel mixture, leading to rough idle and hesitation. Inspect all vacuum lines and connections carefully.
3. Ignition System (Even with New Parts):
* Distributor Cap and Rotor (if applicable): Even with new wires, a worn distributor cap or rotor can cause misfires and rough running. Inspect these components for cracks or wear. (If your Beretta has a distributor).
* Ignition Coil: While less likely if you've had recent issues, a failing ignition coil can cause misfires and poor running.
4. Engine Management System:
* Computer/ECM: In rare cases, a faulty Engine Control Module (ECM) can cause a wide range of problems, including those you describe. This is usually a last resort diagnosis.
Troubleshooting Steps:
1. Check for Vacuum Leaks: Start by carefully inspecting all vacuum lines and connections for cracks or loose fittings. Use a vacuum gauge if possible.
2. Test Fuel Pressure: This is a crucial step to rule out fuel pressure regulator or fuel pump issues. You'll need a fuel pressure gauge.
3. Inspect the MAF Sensor: Clean it with MAF sensor cleaner (follow instructions carefully).
4. Check the O2 Sensor: This requires a multimeter and understanding how to test O2 sensor output.
5. Scan the Engine Codes: Use an OBD-I scanner (your Beretta is likely OBD-I, not OBD-II) to retrieve any diagnostic trouble codes (DTCs) stored by the engine computer. These codes can point directly to the problem.
6. Inspect Distributor Cap and Rotor (If Applicable): Visually check for cracks, wear, or carbon tracking.
Important Note: The strong gas smell is a serious concern. Continuing to drive the car with a rich fuel mixture can lead to damage to the catalytic converter and potentially a fire hazard. It's best to diagnose and repair this issue as soon as possible. If you are not comfortable performing these diagnostic checks yourself, take it to a qualified mechanic.
