When people on here talk about vacuum leaks, does this include the ones the changes the vent flaps for heating/AC? Would leaks in these affect performance/give me absolutely pitiful gas mileage?

These are all messed up in my car, the flaps never worked since we bought the car, then while replacing the heater core, they didn't get fixed/messed up worse. Since then I disconnected the springs from those little airbags and all my vents are open all the time (not perfect but it works). If I could solve my gas mileage/performace/running rich problems by cutting this part of the system off from the rest I'd wet myself.

So what I'm asking is... is this heater vent vacuum system part of the rest/do leaks there matter?

Thanks, Jeremy
MarchingAnt86@juno.com