The vents in the dash are operated by vacuum. THe one door, the blender door, opens and closes based on if you want heat or AC. Chances are there is a vacuum leak to it or inder the dash allowing it to change directions when under an acceleration. When you place that type of load on the engine, the vacuum in the intake drops (normal) and if there are any leaks, other vacuum related systems are affected by it.
Monday, August 17th, 2009 AT 10:10 PM