All the vacuum in the booster of my new '06 V6 6 speed leaks out after 45 minutes of sitting. So I have a rock hard pedel till the engine gets going for a second or two. Just enough time to roll into the curb!! My '03 v6 holds vac. indefinately. Dealer says that it is normal for the booster to let the vac. out the 'check valve' 15-20 minutes after shutting it off. Do they think I am stupid or something?? Or has someone else heard of a check valve on a brake booster that isn't on an '03? What on earth could the benefit be from releasing the vac. in the system?