[Gizmo42]

My first thought was that the VSV for 2wd is sticking. But unplugging it should have no effect if thats the case, unless the movement of unplugging it is enough to cause it to free up. Try switching it into 4wd then smack the 2wd VSV with a screwdriver or something and see if that stops the vacuum on that side.

It seems that it would be odd for the computer to have both activated even if its messed up. If the above doesnt work, unplug the 2wd VSV and put a meter on both terminals of the wiring harness side plug. You should have voltage between them (I'm guessing 12 volts but not sure) in 2wd. Switch to 4wd and see if the voltage goes away. If it does then its the VSV, if not then its the computer. You can double check the readings against the 4wd VSV to be sure the voltage actually goes away on it.