2009 Mitsubishi Endeavor Timing Belt

I recently changed the timing belt in my 2009 Mitsubishi Endeavor (3.8l V6 6G75). I followed all of the appropriate steps in a number of different manuals, but am finding that when the truck sits for an extended period, the timing belt ends up with "slack" in between the left and right camshaft sprokets and the autotensioner is depressed all the way in. It runs perfect when it is warm, but upon cold starts, there is a 2-5 second knocking sound.

Following the installation instructions, the tensioner was adjusted correctly, all timing marks were aligned and there was no play in the belt at all.