Hello,

Today, starting engine, having my foot on cluch pedal, heard a weird noise , like something imitate the sound of engine.

Free the clutch pedal, sound dissappear, then, pres shortly the gas pedal, after released it, same sound for like 5 seconds

What could be?

If related to pressing the clutch pedal then it could be the clutch thrust bearing. If related to the accelerator pedal then then perhaps a squeaky alternator, water pump or lose belt. Video of noise would be helpful.