xantia jumping in first gear and low rpm

[saeedm]

hi everyone
in Iran we have lots of Xantia X2 XU10-J4R non-hydractive
the ones that exceeds like 300k usage, also mine, we have a big problem

when first gear is engaged and acceleration pedal is not pushed and car is moving with engine idle power, -> smallest push on gas pedal -> car jumps forward (it is like releasing clutch rapidly) .no matter how i do, car jumps every time(with smallest touch on gas pedal)
first acceleration is not linear
and when im moving on like 2000rpm, if i release gas pedal , 1 sec later engine loss power like it is braked , and it is not linear deceleration

i replaced idle motor/tps sensor/map sensor/intake air temperature sensor/spark plugs/spark plug boots/engine speed sensor/ignition coil (with original parts- i am xantia original spare part seller)
no changes

what else should i do?
what is the problem?

[xantia_v6]

Is this behaviour all the time or only when the engine is warmed up?

[saeedm]

it happens all the time