I swapped into mine a few weeks ago.(94' 2.5) I robbed one off an 01' 4.0 XJ.
I swapped over the sensors from the 2.5 TB and used a vacuum plug on the unused vacuum port.
There is a noticable power gain,nothing major.
When you first start it the idle is high,but calms down after a minute or so.
You get a "whistle" at certain RPM's.
I do not believe it really changes the MPG any, But I have not ran it enough to know for sure.
Pretty simple swap, 15 minutes or so.
Hope this helps.