Swapping the SLABS didn't change anything... still reading weird Km/H with the scanner. I'm thinking it's in the wires or the ECM, especially since the speedo works fine.

 

That is good news. Finally a code and it is a vss code.

Let is know what happens.

 

FIXED! it was the ECM. It was nasty... which is funny because it looked ok from the outside. I gave it a good scrubbing, with my fingers crossed that I wouldn't break it worse than it already was. Plugged it in, and now my road speed in park is only 0 km per hour. Idles smooth at750ish, doesn't want to die, and it takes off from a stop just fine.