P200E PROPLEMS delay after opening the gasthrottle for about 0,5 sec

Hey People

 

I have a P200e (standard engine)  with an polini exhaust pipe

 

When i close the gasthrottle at higher speed (>80KMH), the engine has a delay[C] after opening the gasthrottle for about 0,5 sec.

what can it be?? suggestions?

 

Greetings from Holland