First, I think you may have two different vacuum leaks. First, the defroster vent is the default location when there is a problem. Check for vacuum leaks under the dash. WIth the engine running, you may get lucky and hear a hissing sound from the leak.
As far as the 4wd, can you put it in 4wd Lo? NOTE: I am trying to determine if there is a problem with the transfer case or front axle. If it goes in low lock, even if only the rear wheels have power, the transfer case is working. If that is the case, check for vacuum leaks to the front axle actuator.
Let me know what you find.
Monday, March 15th, 2010 AT 10:23 PM