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Did the check engine light stay on with the engine running? If it did, the first thing you need to do is check for diagnostic trouble codes. Most parts stores will do it for free, but since the vehicle is not safe to drive, see if they will lend or rent one to you.
Here is a quick video showing how one is used:
The first thing I would check is the throttle position sensor. Here are the directions for removal and replacement. I'm adding them to help you inspect it. Make sure the connector isn't damaged or loose. The attached pictures correlate with the directions.
2004 Chevrolet Impala V6-3.4L VIN E
Vehicle Powertrain Management Fuel Delivery and Air Induction Sensors and Switches - Fuel Delivery and Air Induction Throttle Position Sensor Service and Repair Procedures
THROTTLE POSITION (TP) SENSOR REPLACEMENT
1. Disconnect the fuel lines.
2. Disconnect the throttle position (TP) sensor electrical connector.
3. Remove the TP sensor screws.
4. Remove the TP sensor and the O-ring.
1. Install the TP sensor O-ring to the TP sensor.
2. Install the TP sensor.
3. Apply thread-locking compound LOCTITE(R) 262, GM P/N 12345493 (Canadian P/N 10953488) or equivalent to the TP sensor screws.
NOTE: Refer to Fastener Notice in Service Precautions.
4. Install the TP sensor screws.
Tighten the screws to 2.0 N.m (18 lb in).
5. Connect the TP sensor electrical connector.
6. Connect the fuel lines.
Let me know about the diagnostic trouble codes and if this helps.
Images (Click to enlarge)
Friday, September 20th, 2019 AT 7:12 PM