P0106 = Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem.
I have never done this job on the V6 - only the 280E I6 twincam - so I'm trying to help. First thing to do is to check for any air leaks into the manifold after the MAF
After doing that the manifold pressure sensor becomes suspect. See points 140 on the engine wiring diagram below - that connects to the manifold pressure sensor.
I do not know the position of this sensor on the manifold & I can't find a diagram of it's position. I will keep looking. The knock sensor is about dead centre of the manifold - item 35. You are going to have to pull off the airbox and do some scratching. There is an aneroid sensor somewhere that could also be suspect - they usually get clogged with dust. I hope this helps - Good luck!