Are you sure that the Acadia is simply not tracking or turning properly.

In my opinion, the blue taps and crimp connectors should not be used on any critical wiring or connections exposed to weather or spray.

Whenever I must do electrical work, I solder everything and insulate using shrink tubing. If the wires are bundled, I also stagger the connections so none are able to rub against another.

I've had too many breaks and shorts occur on "Factory" harnesses and connectors to take the chance. Once they are done properly, there is almost no chance of problems in the same place.

Sounds a little like the exhaust brake is set to come on when you lift your foot off of the accelerator then disengages as your foot just touches the accelerator again. Try doing this with your exhaust brake set to "off".