my CEL is on and my car just aint running right. its a 99 b5 wagon. it likes to not take off from a stop and just bog down and not rev. i had the OBDII codes checked there were 2 that came up. both said fuel/air metering. but also i hear a loud hissing with the hood open but if you rev the engine quick it goes away for a second. i assume that is a vaccum leak but i cant figure out where its coming from? any help would be greatly appreciated thanks.