Is the vacuum gauge reading eratically on tickover? If you are certain there are no hoses split, i would advide removing the brather pipe, and blocking the entry to the air boc temporarily, and seeing if it will itdle, and then if no use, also remove and block off the pipe to the brake servo. And if its still doing it, you may of blown the intercooler apart or blown out an inlet manifold gasket as Daz said