Nissan Cabstar

Olá amigos, espero que você possa me ajudar.
Problem:
Nissan Cabstar, at optimal engine temperature and in a maximum parliament suddenly, if you continue to thrown through the white smoke escape (only on these occasions) and make deflagrations (explosions), as soon as it stops accelerating and the revolutions go down to idle can be accelerated and the engine replaces without problems until it reaches the regime of revolutions between 3000 and then.
Analisei o pedal eletrônico, mudei de diesel e filtros de ar, provou o fluxo de combustível e estou perdido, aprecio antecipadamente qualquer ajuda e orientação.