Greetings!I would check the fuel pressure regulator. It is located on the fuel rail. It is round, about a quarter size and has a vacuum line going to it. If the regulator is leaking gas than it can cause this problem. Pull off the vacuum line that goes to the regulator. Be absolutely sure there is no gas in the vaccum line. If there is, the diaphram has ruptured and there is gas entering the engine that is not accounted for and the regulator will need to be replaced!