Engine Lacks Power

Ensure throttle valve opens completely when accelerator pedal is fully depressed.
Ensure air intake system is unrestricted.
Check Mass Airflow (MAF) sensor.
Check intake manifold change-over valve.
Ensure fuel system pressure and volume are correct.
Ensure base timing is correct and timing advance system is functional.
Check Engine Coolant Temperature (ECT) sensor operation.
Check transmission for correct downshift (A/T).
Check fuel tank filler tube for tampering of restrictor. If tampering has occurred, check catalytic converter for lead contamination and exhaust system restriction.
Check for poor quality fuel containing insufficient cleaning additives.

NOTE: Prolonged use of poor quality fuel can cause injector clogging and carbon build-up on intake system.