What might cause a Toyota Camry to lose engine power?

These are some things that will cause an engine to lose power

1. Missfire

2. Air leaks

3. Incorrect ignition timing

4. Incorrect cam timing (belt has jumped)

5. Overheating

6. Contaminated fuel

7. Auto box failiure

8. Clutch slipping

9. Brakes stuck on

10. Seized wheel bearing

11. Engine management fault ( car in limp home mode )

Those are just a few of the faults that I have come across

In my days as a breakdown mechanic.

Very dificult to diagnose without seeing the car

but I hope this will point you in the right direction

Best wishes

Good luck