Coming from this thread that wasn't answered:
post5748105.html?hilit=STFT%2025%#p5748105

2004 Xterra 2.4L Short Term Fuel Trims (STFT) numbers are interesting.

The Xterra I'm looking at has this issue as well.

Engine at Idle - Starts at 0% and climbs to 25%, then engine slightly stumbles and STFT goes back to 0% and the process starts over.

I'm thinking a vacuum leak somewhere causing a lean condition that the ECM is compensating for - thoughts?

Well, since I've gotten no replies I'm going ahead with the first item on the list: vacuum lines.

I've ordered new lines and will be replacing all of them as they are 18 years old.

I'll keep everyone updated along the way as I've got a lot of things to repair on this old truck.