I have a 1978 trans am, with the pontiac 400 motor with the high compression heads(350). The car was running great untill about four days ago. All of a sudden it started bogging down real bad, and shutting off. I have already rebuilt the carb on it, I check the distributor and it was fine, and just took off the intake manafold and the gaskest were fine. Could anybody please tell me what else could be wrong. It is acting like there is a vacum leak somewhere, but i can't seem to find it. Any Ideas?