Possible Causes and Troubleshooting:
* Throttle Position Sensor (TPS): This sensor tells the computer the throttle's position. A faulty TPS can send incorrect signals, leading to excessive fuel delivery under acceleration. Test the TPS voltage output with a multimeter while slowly opening the throttle. Compare your readings to factory specifications (found in a repair manual). Replacement is relatively inexpensive.
* Mass Airflow Sensor (MAF) or Air Flow Meter (AFM): This sensor measures the amount of air entering the engine. A dirty or faulty MAF/AFM will cause incorrect fuel delivery calculations. Clean the MAF sensor with MAF sensor cleaner (following the cleaner's instructions carefully – don't touch the sensor element). If cleaning doesn't help, replacement is necessary.
* Fuel Injectors: While less likely given the starting and idling behavior, clogged or sticking fuel injectors could contribute to the bogging. A fuel injector cleaner might help, but a professional fuel injection service or injector flow testing is more definitive.
* Computer (PCM/ECM): The Powertrain Control Module (PCM) or Engine Control Module (ECM) controls fuel delivery. A faulty PCM is less likely, but possible. Diagnosis requires advanced diagnostic tools.
* Vacuum Leaks: A vacuum leak can disrupt the air/fuel mixture, leading to poor performance. Inspect all vacuum hoses and connections for cracks, leaks, or loose fittings.
* Fuel Pressure Regulator: This regulator maintains consistent fuel pressure. A faulty regulator can cause excessive pressure, leading to a rich fuel mixture. Testing fuel pressure is crucial (requires a fuel pressure gauge).
Before you continue:
* Check the fuel filter: Though you replaced the pump, a clogged fuel filter could still restrict fuel flow, especially under higher demand during acceleration.
Recommended Steps:
1. Check fuel pressure: Use a fuel pressure gauge to measure fuel pressure at idle and during acceleration. Compare the readings to factory specifications.
2. Inspect and test the TPS: As mentioned above, this is a common culprit.
3. Clean the MAF/AFM sensor: A dirty sensor can easily cause this problem.
4. Check for vacuum leaks: Carefully inspect all vacuum hoses and connections.
5. Consider a professional diagnosis: If you're not comfortable with these checks, a mechanic with experience in fuel injection systems can use diagnostic tools to pinpoint the problem more accurately.
Replacing parts haphazardly without proper diagnosis is inefficient and expensive. Systematic troubleshooting will save you time and money. A repair manual specific to your 1986 Chrysler Fifth Avenue will provide valuable diagrams and specifications.
