DTC code P0174. What are the likely causes based on the following symptoms? on 2005 Mercedes-Benz C240 4MATIC

The car has problems starting, specially when warm. Sometimes idle level too low, this gets worse the longer the car runs. Sometimes pressing the gas pedal does not obtain an immediate response, pressing the gas pedal slowly seems to solve the problem. I have checked the vacuum seal on the exhaust.

Asked by for the 2005 Mercedes-Benz C240 4MATIC