I chased the same problem for months and thousands of dollars. I even changed the timing chain once the CEL came on. I traded in the 2012 after the timing chain didn't even correct the problem.
Dealership blew the engine shortly after my trade, found a faulty crank shaft bearing was to blame for that problem.
They installed a new engine and have told me that the hesitation / shudder has gone away. Talking to the salesman that I purchased my 2017 Acadia from, he tells me that they damaged the torque converter while attempting to align the new engine and had to replace it.
I recall another member here describing the same hesitation / shudder problem and replacing the torque converter to correct it.. that could be a good starting point.
I'm not sure if the torque converter could have caused the bearing to go bad (the whole vehicle shook badly when the hesitation occurred, and I'm sure that was felt through the engine too.
I tried the following to no avail....
2008 SLE AWD 8psg Medium Brown Metallic RIP<br />2010 SLE2 AWD 8psg Summit White / Sunroof / tow pkg Traded-IN<br />2012 SLE2 AWD 8psg QuickSilver / Sunroof / Bose Traded-IN<br />2017 SLT1 AWD 7psg Summit White / Navigation / Sunroof / Bose / Tow pkg