Fuel Delivery Issues:
* Throttle Position Sensor (TPS): A faulty TPS provides inaccurate information to the engine computer (ECM), leading to poor fuel mixture and rough running, especially when warm. This is a very common cause of these symptoms.
* Mass Airflow Sensor (MAF): Similar to the TPS, a dirty or malfunctioning MAF sensor provides incorrect air flow data, again leading to poor fuel mixture. Cleaning it (carefully!) is often a first step.
* Fuel injectors: Clogged or failing injectors can cause inconsistent fuel delivery, resulting in rough idle and hesitation during acceleration. This is more likely to be a gradual problem rather than a sudden one.
* Fuel pressure regulator: A faulty regulator might deliver incorrect fuel pressure, leading to a lean or rich condition.
* Fuel pump: A weak fuel pump might not supply enough fuel under load (acceleration), causing hesitation.
Ignition System Problems:
* Ignition coil: A failing ignition coil can cause misfires, resulting in a rough idle and poor acceleration.
* Spark plugs and wires: Worn, fouled, or damaged spark plugs and wires can lead to misfires. These are relatively inexpensive to replace.
* Distributor cap and rotor (if applicable): Cracks or corrosion in these components can disrupt the spark delivery.
Vacuum Leaks:
* Vacuum hoses: Cracked, loose, or disconnected vacuum hoses can disrupt the engine's operation, leading to rough idling and poor performance. Inspect all vacuum lines carefully.
* Intake manifold gasket: A leak in the intake manifold gasket can cause significant vacuum issues.
Other Possibilities:
* PCV valve: A clogged positive crankcase ventilation (PCV) valve can cause excessive crankcase pressure, affecting engine performance.
* Oxygen sensor: While less likely to cause the specific symptoms you described, a faulty oxygen sensor can contribute to poor fuel mixture.
* Engine coolant temperature sensor: An inaccurate reading from this sensor can cause the ECM to adjust the fuel mixture incorrectly.
Troubleshooting Steps:
1. Check for trouble codes: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs) stored in the ECM. This can pinpoint the problem area.
2. Visual inspection: Inspect all vacuum hoses, spark plug wires, and other easily accessible components for damage or leaks.
3. Clean the MAF sensor: Carefully clean the MAF sensor with MAF sensor cleaner.
4. Check fuel pressure: If possible, measure the fuel pressure to ensure it's within specifications.
5. Replace spark plugs and wires: These are relatively inexpensive and often a good preventative measure.
Important Note: Without further diagnostic testing, it's difficult to pinpoint the exact cause. If you're not comfortable performing these checks yourself, take your Tahoe to a qualified mechanic for proper diagnosis and repair. They have the tools and expertise to accurately identify the problem.
