2003 Chevy Trailblazer Engine whine & now belt squealin

This is my first post. For quite awhile now when I accelerate there is a loud whining noise coming from the engine and it feels like it's dragging (lost power). But more recently, along w the whining, now when I give it gas the belt or a pulley or something is squealing. My post is two fold here...

I had the fan clutch and water pump replaced about a year ago. I've been reading and think at least the belt squeal is either the idler pulley or tensioner, which leads to my first issue. I've purchased a new idler pulley, but don't see any way I can loosen the tensioner as it is below the fan (tight location) and don't see an easy way to access from the underside. Any ideas how to gain access to the tensioner so I can replace the idler pulley? (see pic of V8 diagram)

And I guess my second part of this post is wondering if the belt issue or pulley would also be causing the whining noise.