I think it's all in post #19

You could read up on fuel trims,too

 

I completely forgot I even started this thread, so anyways, I'm back just for the sake of others experiencing this issue.

Turns out that the MAP sensor was the problem(why it did not flare a code, I'll never know). Now she idles fine, no restricted performance or anything like that.

A few days after the replacement of the MAP sensor, a code did pop up for a pre-cat O2 sensor, might have been the very source of the issue, and a worn out MAP sensor simply didn't help. Regardless, the Jag is running like a charm again.

Thanks so much everyone for all the support along the way!

 

Good deal!!!! Thanks for posting the follow-up. I hate going thought these threads and they just fizzle out with no answer... Doesn't help anyone. Interesting how everything directed you elsewhere from the MAP sensor, though.