the problem is that it is not 100% consistent, so I can have laggy throttle pedal when the tank is almost empty, but most of the time it happens when the tank is almost full or at 3/4, 2/3... there is some connection, I'm sure!
maybe I should do this ITB:
Knowledgebase - Infinitihelp.com Forums - VENT CONTROL VALVE REPLACEMENT ?