Backfiring in a car could be caused by a few different issues. Since you have already changed the spark plugs and fuel pump, here are some other possible reasons for the backfiring in your 4AFE engine:

1. **Ignition Timing**: Incorrect ignition timing can cause the air-fuel mixture to not ignite at the right time, leading to backfiring. You may want to check and adjust the ignition timing if needed.

2. **Vacuum Leaks**: A vacuum leak can disrupt the air-fuel mixture ratio, causing backfiring. Check for any cracked or disconnected vacuum hoses and replace or reconnect them as necessary.

3. **Faulty Ignition System Components**: Issues with components such as the ignition coil, distributor, or ignition wires can lead to misfiring and backfiring. Ensure that these components are functioning properly.

4. **Clogged Exhaust System**: A clogged catalytic converter or exhaust system can cause backfiring. Check for any obstructions in the exhaust system and replace any faulty parts.

5. **Fuel System Issues**: Apart from the fuel pump, issues like a clogged fuel injector or a malfunctioning fuel pressure regulator can lead to backfiring. Consider checking and cleaning the fuel injectors and testing the fuel pressure regulator.

It's recommended to inspect each of these potential causes to pinpoint the exact reason for the backfiring in your 4AFE engine. Remember to also consider factors like engine overheating or poor fuel quality, as they can also contribute to backfiring issues.