Insufficient Engine Power

Check fuel injectors.
Ensure fuel tanks are 1/4 full (MINIMUM).
Check for air inlet restriction.
Ensure fuel pressure is correct.
Check for restricted exhaust.
Check for restricted fuel filter.
Check for restricted air filter.
Check coolant temperature sensor.
Check CNG temperature sensor.
Check CNG low pressure sensor.
Check intake air temperature sensor.
Check ignition and coil circuit.
Check MAP sensor.
Check oxygen sensor.
Check crankshaft position sensor.
Check intake and exhaust system.
Check EGR system.