These 16V frequently demand our attention and while I've fixed mine I've never determined what I did to fix it. I've always got idle stabilization problems. It idles fine for a few months, then it doesn't. I unplug everything, everything checks okay, I put it back together and it runs fine ... for a couple months.
I had some knocking in my 16V on hot days while AXing. My mechanic gave me a can of BG44 or whatever the name of it is to add to the fuel (cleans injectors and valves). Haven't noticed any knocking since.