* Fuel Pump: A weak fuel pump may be unable to supply enough fuel when the engine demands more under acceleration. It might work fine at idle but struggle when the engine needs more fuel.
* Fuel Filter: A clogged fuel filter restricts fuel flow, causing similar symptoms to a weak fuel pump.
* Throttle Position Sensor (TPS): This sensor tells the computer the throttle position. A faulty TPS can cause incorrect fuel/air mixture calculations, leading to poor performance, especially under acceleration.
* Mass Air Flow Sensor (MAF): If the MAF sensor is dirty or faulty, it won't accurately measure the incoming air, leading to a poor fuel mixture. This is another likely suspect for problems specifically under load.
* Ignition System: Problems with the distributor cap, rotor, spark plug wires, or even the ignition coil itself could manifest as poor performance or stalling, especially under load. A weak coil might be able to provide enough spark at idle but not enough when the engine is working harder.
* Transmission Issues (Less Likely, But Possible): While less probable given the description, a problem within the transmission itself (low fluid, worn components) could contribute to the car struggling to move effectively, potentially causing the engine to stall due to increased load.
Troubleshooting Steps:
1. Check the fuel pressure: This is the most crucial step. You'll need a fuel pressure gauge to measure the pressure at the fuel rail. Compare this to the manufacturer's specification. Low pressure points to a fuel pump or filter issue.
2. Inspect the fuel filter: It's relatively easy and inexpensive to replace the fuel filter. A clogged filter is a common cause of these symptoms.
3. Check the spark: Examine the spark plugs, wires, distributor cap, and rotor for wear or damage. A weak spark under load will cause the engine to struggle.
4. Clean the MAF sensor: Use a MAF sensor cleaner (following the instructions carefully) to clean the sensor element. A dirty sensor can cause similar issues.
5. Consider the TPS: While testing a TPS requires more specialized tools, it's another likely candidate. You might find diagnostic information online or consult a repair manual.
Important Note: Since the car stalls when put into gear, the problem is likely related to the engine's inability to cope with the increased load. Focusing on fuel delivery and the ignition system is the most efficient approach. If you're not comfortable working on your car yourself, taking it to a mechanic is recommended. They can diagnose the problem accurately and perform the necessary repairs safely.
