[RahX]

the brake booster, which is connected to your master cylinder, has a big vacuum line going to it. there is a plastic piece on this vacuum line that holds vacuum in the booster. start and run the van for a min or so and shut it down. unplug the hose from the booster and listen for it to suck air. if it does then dont worry about that. the 3.8s have a problem with the upper plenum o-rings leaking. MIGHT be your problem but they usually set a code. also the MAF might need to be cleaned but those usually result in a dead spot when youre on the gas but they can affect idle quality.