Quote Originally Posted by Dee23 View Post
Yes, vacuum leaks can interfere with getting optimum MPG. Vac leaks arent monitored, so the MAF,IAT,IAC, arent reading that extra amount of air so the meterization gets thrown off and also it can be dirty air depending on how bad the leak is bc its not being filtered either by your air filter.

If i can remember right, I think the Vac PSI should be around 19-22psi but if u do manage to get the VAC gauge just hook it up to the brake booster line. For a easy quick check, use CARB cleaner and spray on all the VAC lines and listen for the change of the idle.
Come to think of it I need to check and probably clean my air filter. Just changed it about six months ago but I drive a dirt road on a normal basis