I have a doubt with my Frontier: when starting in first gear, the van works perfectly well but, when revolutions reach 4500 per minute and making a fast change to second gear and pressing the accelerator, it does not respond as it should. It feels as if it lost power and choked. I've done its complete tuning and I only use 92 octanes fuel. There is no oil nor liquid leakage in the engine and the transmission has no escapes either.