A code P0174 may mean that one or more of the following has happened:
The MAF (Mass Air Flow) Sensor is dirty or faulty. Note: The use of "oiled" air filters can cause the MAF to become dirty if the filter is over-oiled.
There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak downstream of the MAF sensor.
going with the other answer, pop the hood and listen for a hissing sound. another way is to spray carb cleaner on vacumn leaks. if the engine surges when you do this, you just found your leak. a common leak on these vans is the PCV hose. good luck.
